Over nineteen hundred miles east of The Twin Cities of Helium, at about Lat. 30 degrees S., Lon. 172 degrees E., lies Zodanga. It has ever been a hotbed of sedition since the day that I led the fierce green hordes of Thark against it and, reducing it, added it to the Empire of Helium.

Within its frowning walls lives many a Zodangan who feels no loyalty for Helium; and here, too, have gathered numbers of the malcontents of the great empire ruled over by Tardos Mors, Jeddak of Helium. To Zodanga have migrated not a few of the personal and political enemies of the house of Tardos Mors and of his son-in-law, John Carter, Prince of Helium.

I visited the city as seldom as possible, as I had little love either for it or its people; but my duties called me there occasionally, principally because it was the headquarters of one of the most powerful guilds of assassins on Mars.

The land of my birth is cursed with its gangsters, its killers, and its kidnappers but these constitute but a slight menace as compared with the highly efficient organizations that flourish upon Mars. Here assassination is a profession; kidnaping, a fine art. Each has its guild, its laws, its customs, and its code of ethics; and so widespread are their ramifications that they seem inextricably interwoven into the entire social and political life of the planet.

For years I have been seeking to extirpate this noxious system, but the job has seemed a thankless and hopeless one. Entrenched behind age-old ramparts of habit and tradition, they occupy a position in the public consciousness that has cast a certain glamour of romance and honor upon them.

The kidnappers are not in such good odor, but among the more notorious assassins are men who hold much the same position in the esteem of the masses as do your great heroes of the prize ring and the baseball diamond.

Furthermore, in the war that I was waging upon them, I was also handicapped by the fact that I must fight almost alone, as even those of the red men of Mars who felt as I did upon the subject also believed that to take sides with me against the assassins would prove but another means for committing suicide. Yet I know that even this would not have deterred them, had they felt that there was any hope of eventual success.

That I had for so long escaped the keen blade of the assassin seemed little less than a miracle to them, and I presume that only my extreme self-confidence in my ability to take care of myself prevented me from holding the same view.

Dejah Thoris and my son, Carthoris, often counseled me to abandon the fight; but all my life I have been loath to admit defeat, nor ever have I willingly abandoned the chance for a good fight.

Certain types of killings upon Mars are punishable by death, and most of the killings of the assassins fell in such categories. So far, this was the only weapon that I had been able to use against them, and then not always successfully, for it was usually difficult to prove their crime, since even eyewitnesses feared to testify against them.

But I had gradually evolved and organized another means of combating them. This consisted of a secret organization of super-assassins. In other words, I had elected to fight the devil with fire.

When an assassination was reported, my organization acted in the role of detective to ferret out the murderer. Then it acted as judge and jury and eventually as executioner. Its every move was made in secret, but over the heart of each of its victims an "X" was cut with the sharp point of a dagger.

We usually struck quickly, if we could strike at all; and soon the public and the assassins learned to connect that "X" over the heart as the mark of the hand of justice falling upon the guilty; and I know that in a number of the larger cities of Helium we greatly reduced the death rate by assassination. Otherwise, however, we seemed as far from our goal as when we first started.

Our poorest results had been gained in Zodanga; and the assassins of that city openly boasted that they were too smart for me, for although they did not know positively, they guessed that the X's upon the breasts of their dead comrades were made by an organization headed by me.

I hope that I have not bored you with this exposition of these dry facts, but it seemed necessary to me that I do so as an introduction to the adventures that befell me, taking me to a strange world in an effort to thwart the malign forces that had brought tragedy into my life.

In my fight against the assassins of Barsoom, I had never been able to enlist many agents to serve in Zodanga; and those stationed there worked only in a half-hearted manner, so that our enemies had good reason to taunt us with our failure.

To say that such a condition annoyed me would be putting it mildly; and so I decided to go in person to Zodanga, not only for the purpose of making a thorough investigation, but to give the Zodangan assassins a lesson that would cause them to laugh out of the other side of their mouths.

I decided to go secretly and in disguise, for I knew that if I were to go there as John Carter, Warlord of Mars, I could learn nothing more than I already knew.

Disguise for me is a relatively simple matter. My white skin and black hair have made me a marked man upon Mars, where only the auburn-haired Lotharians and the totally bald Therns have skin as light colored as mine.

Although I had every confidence in the loyalty of my retainers, one never knows when a spy may insinuate himself into the most carefully selected organization.

For this reason, I kept my plans and preparations secret from even the most trusted members of my entourage.

In the hangars on the roof of my palace are fliers of various models, and I selected from among them a one-arm scout flier from which I surreptitiously removed the insignia of my house. Finding a pretext to send the hangar guard away for a short time early one evening, I smuggled aboard the flier those articles that I needed to insure a satisfactory disguise. In addition to a red pigment for my own skin and paints for the body of the flier, I included a complete set of Zodangan harness, metal, and weapons.

That evening I spent alone with Dejah Thoris; and about twenty-five xats past the eighth zode, or at midnight earth time, I changed to a plain leather harness without insignia, and prepared to leave upon my adventure.

"I wish you were not going, my prince; I have a premonition that -- well -- that we are both going to regret it."

"The assassins must be taught a lesson," I replied, "or no one's life will be safe upon Barsoom. By their acts, they have issued a definite challenge; and that I cannot permit to go unnoticed."

"I suppose not," she replied. "You won your high position here with your sword; and by your sword I suppose you must maintain it, but I wish it were otherwise."

I took her in my arms and kissed her and told her not to worry -- that I would not be gone long. Then I went to the hangar on the roof.

The hangar guard may have thought that it was an unusual time of night for me to be going abroad, but he could have had no suspicion as to my destination. I took off toward the West and presently was cutting the thin air of Mars beneath the myriad stars and the two gorgeous satellites of the red planet.

The moons of Mars have always intrigued me; and tonight, as I gazed upon them, I felt the lure of the mystery that surrounds them. Thuria, the nearer moon, known to earth men as Phobos, is the larger; and as it circles Barsoom at a distance of only 5800 miles, it presents a most gorgeous sight. Cluros, the farther moon, though only a little smaller in diameter than Thuria, appears to be much smaller because of the greater distance of its orbit from the planet, lying as it does, 14,500 miles away.

For ages, there was a Martian legend, which remained for me to explode, that the black race, the so-called First-born of Barsoom, lived upon Thuria, the nearer moon; but at the time I exposed the false gods of Mars, I demonstrated conclusively that the black race lived in the Valley Dor, near the south pole of the planet.

Thuria, seemingly hanging low above me, presented a gorgeous spectacle, which was rendered still more remarkable by the fact that she apparently moved through the heavens from west to east, due to the fact that her orbit is so near the planet she performs a revolution in less than one-third of that of the diurnal rotation of Mars. But as I watched her this night in dreamy fascination, little could I guess the part that she was so soon to play in the thrilling adventures and the great tragedy that lay just beyond my horizon.

When I was well beyond The Twin Cities of Helium, I cut off my running lights and circled to the South, gradually heading toward the East until I held a true course for Zodanga. Setting my destination compass, I was free to turn my attention to other matters, knowing that this clever invention would carry the ship safely to its destination.

My first task was to repaint the hull of the flier. I buckled straps onto my harness and onto rings in the gunwale of the craft; and then, lowering myself over the side, I proceeded to my work. It was slow work, for after painting as far as I could reach in all directions, I had to come on deck and change the position of the straps, so that I could cover another portion of the hull. But toward morning it was finally accomplished, though I cannot say that I looked with pride upon the result as anything of an artistic achievement. However, I had succeeded in covering the old paint and thus disguising the craft insofar as color was concerned. This accomplished, I threw my brush and the balance of the paint overboard, following them with the leather harness that I had worn from home.

As I had gotten almost as much paint upon myself as upon the hull of the boat, it took me some little time to erase the last vestige of this evidence that would acquaint a discerning observer with the fact that I had recently repainted my craft.

This done, I applied the red pigment evenly to every square inch of my naked body; so that after I had finished, I could have passed anywhere on Mars as a member of the dominant red race of Martians; and when I had donned the Zodangan harness, metal, and weapons, I felt that my disguise was complete.

It was now mid-forenoon; and, after eating, I lay down to snatch a few hours of sleep.

Entering a Martian city after dark is likely to be fraught with embarrassment for one whose mission may not be readily explained. It was, of course, possible that I might sneak in without lights; but the chances of detection by one of the numerous patrol boats was too great; and as I could not safely have explained my mission or revealed my identity, I should most certainly be sent to the pits and, doubtless, receive the punishment that is meted to spies -- long imprisonment in the pits, followed by death in the arena.

Were I to enter with lights, I should most certainly be apprehended; and as I should not be able to answer questions satisfactorily, and as there would be no one to sponsor me, my predicament would be almost equally difficult; so as I approached the city before dawn of the second day, I cut out my motor and drifted idly well out of range of the searchlights of the patrol boats.

Even after daylight had come, I did not approach the city until the middle of the forenoon at a time when other ships were moving freely back and forth across the walls.

By day, and unless a city is actively at war, there are few restrictions placed upon the coming and going of small craft. Occasionally the patrol boats stop and question one of these; and as fines are heavy for operating without licenses, a semblance of regulation is maintained by the government.

In my case, it was not a question of a license to fly a ship but of my right to be in Zodanga at all; so my approach to the city was not without its spice of adventure.

At last the city wall lay almost directly beneath me; and I was congratulating myself upon my good fortune, as there was no patrol boat in sight; but I had congratulated myself too soon, for almost immediately there appeared from behind a lofty tower one of those swift little cruisers that are commonly used in all Martian cities for patrol service, and it was headed directly toward me.

I was moving slowly, so as not to attract unfavorable attention; but I can assure you that my mind was working rapidly. The one-man scout flier that I was using is very fast, and I might easily have turned and outdistanced the patrol boat; however, there were two very important objections to such a plan. One was that, unquestionably, the patrol boat would immediately open fire on me with the chances excellent that they would bring me down. The other was, that should I escape, it would be practically impossible for me to enter the city again in this way, as my boat would be marked; and the entire patrol system would be on the lookout for it.

The cruiser was steadily approaching me, and I was preparing to bluff my way through with a cock-and-bull story of having been long absent from Zodanga and having lost my papers while I was away. The best that I could hope from this was that I should merely be fined for not having my papers, and as I was well supplied with money, such a solution of my difficulties would be a most welcome one.

This, however, was a very slim hope, as it was almost a foregone conclusion that they would insist upon knowing who my sponsor was at the time my lost papers were issued; and without a sponsor I would be in a bad way.

Just as they got within hailing distance, and I was sure that they were about to order me to stop, I heard a loud crash above me; and glancing up, I saw two small ships in collision. I could see the officer in command of the patrol boat plainly now; and as I glanced at him, I saw him looking up. He barked a short command; the nose of the patrol boat was elevated; and it circled rapidly upward, its attention diverted from me by a matter of vastly greater importance.

While it was thus engaged, I slipped quietly on into the city of Zodanga.

At the time, many years ago, that Zodanga was looted by the green hordes of Thark, it had been almost completely razed. It was the old city with which I had been most familiar, and I had visited the rebuilt Zodanga upon but one or two occasions since.

Cruising idly about, I finally found that for which I sought -- an unpretentious public hangar in a shabby quarter of the city. There are quarters in every city with which I am familiar where one may go without being subjected to curious questioning, so long as one does not run afoul of the officers of the law. This hangar and this quarter of Zodanga looked such a place to me.

The hangar was located on the roof of a very old building that had evidently escaped the ravages of the Tharks. The landing space was small, and the hangars themselves dingy and unkempt.

As my craft settled to the roof, a fat man, well smeared with black grease, appeared from behind a flier upon the engine of which he was evidently working.

He looked at me questioningly, and I thought with none too friendly an expression. "What do you want?" he demanded.

"Is this a public hangar?"

"Yes."

"I want space for my craft."

"Have you got any money?" he demanded.

"I have a little. I will pay a month's rental in advance," I replied.

The frown melted from his face. "That hangar there is vacant," he said, pointing. "Run her in there."

Having housed my flier and locked the controls, I returned to the man and paid him.

"Is there a good public house near by?" I asked, "one that is cheap and not too dirty."

"There is one right in this building," he replied, "as good as any that you will find around here."

This suited me perfectly, as when one is on an adventure of this nature, one never knows how quickly a flier may be required or how soon it may be all that stands between one and death.

Leaving the surly hangar proprietor, I descended the ramp that opened onto the roof.

The elevators, ran only to the floor below the roof, and here I found one standing with its door open. The operator was a dissipated looking young fellow in shabby harness.

"Ground floor?" he asked.

"I am looking for lodgings," I replied. "I want to go to the office of the public house in this building."

He nodded, and the elevator started down. The building appeared even older and more dilapidated from the inside than the out, and the upper floors seemed practically untenanted.

"Here you are," he said presently, stopping the elevator and opening the door.

In Martian cities, public houses such as this are merely places to sleep. There are seldom but few, if any, private rooms. Along the side walls of long rooms are low platforms upon which each guest places his sleeping silks and furs in a numbered space allotted to him.

Owing to the prevalence of assassination, these rooms are patrolled night and day by armed guards furnished by the proprietor; and it is largely because of this fact that private rooms are not in demand. In houses that cater to women, these guests are segregated; and there are more private rooms and no guards in their quarters, as the men of Barsoom seldom, if ever, kill a woman, or I may qualify that by saying that they do not employ assassins to kill them, ordinarily.

The public house to which chance had led me catered only to men. There were no women in it.

The proprietor, a burly man whom I later learned was formerly a famous panthan, or soldier of fortune, assigned me a sleeping place and collected his fee for a day's lodging; and after directing me to an eating-place in response to my inquiries, left me.

Scarcely any of the other guests were in the house at this hour of the day.

Their personal belongings, their sleeping silks and furs, were in the spaces allotted to them; and even though there had been no guards patrolling the room, they would have been safe, as thievery is practically unknown upon Mars.

I had brought with me some old and very ordinary sleeping silks and furs and these I deposited upon the platform. Sprawled in the adjoining space was a shifty-eyed individual with an evil face. I had noticed that he had been eyeing me surreptitiously ever since I had entered. At last he spoke to me.

"Kaor!" he said, using the familiar form of Martian greeting.

I nodded and replied in kind.

"We are to be neighbors," he ventured.

"So it would seem," I replied.

"You are evidently a stranger, at least in this part of the city," he continued.

"I overheard you asking the proprietor where you could find an eating-place. The one he directed you to is not as good as the one that I go to. I am going there now; if you'd like to come along, I'll be glad to take you."

There was a furtiveness about the man that, in connection with his evil face, assured me that he was of the criminal class; and as it was among this class that I expected to work, his suggestion dovetailed nicely with my plans; so I quickly accepted.

"My name is Rapas," he said, "they call me Rapas the Ulsio," he added, not without a touch of pride.

Now I was sure that I had judged him correctly, for Ulsio means rat.

"My name is Vandor," I told him, giving him the alias I had selected for this adventure.

"By your metal, I see that you are a Zodangan," he said, as we walked from the room to the elevators.

"Yes," I replied, "but I have been absent from the city for years. In fact, I have not been here since it was burned by the Tharks. There have been so many changes that it is like coming to a strange city."

"From your looks, I'd take you to be a fighting man by profession," he suggested.

I nodded. "I am a panthan. I have served for many years in another country, but recently I killed a man and had to leave." I knew that if he were a criminal, as I had guessed, this admission of a murder upon my pan would make him freer with me.

His shifty eyes glanced quickly at me and then away; and I saw that he was impressed, one way or another, by my admission. On the way to the eating-place, which lay in another avenue a short distance from our public house, we carried on a desultory conversation.

When we had seated ourselves at a table, Rapas ordered drinks; and immediately after he had downed the first one his tongue loosened.

"Are you going to remain in Zodanga?" he asked.

"That depends upon whether or not I can find a living here," I replied. "My money won't last long; and, of course, leaving my last employer under the circumstances that I did, I have no papers; so I may have trouble in finding a place at all."

While we were eating our meal, Rapas continued to drink; and the more he drank the more talkative he became.

"I have taken a liking to you, Vandor," he announced presently; "and if you are the right kind, as I think you are, I can find you employment." Finally he leaned close to me and whispered in my ear. "I am a gorthan," he said.

Here was an incredible piece of good fortune. I had hoped to contact the assassins, and the first man whose acquaintance I had made admitted that he was one.

I shrugged, deprecatively.

"Not much money in that," I said.

"There is plenty, if you are well connected," he assured me.

"But I am not connected well, or otherwise, here in Zodanga," I argued, "I don't belong to the Zodangan guild; and, as I told you, I had to come away without any papers."

He looked around him furtively to see if any were near who might overhear him.

"The guild is not necessary," he whispered; "we do not all belong to the guild."

"A good way to commit suicide," I suggested.

"Not for a man with a good head on him. Look at me; I am an assassin, and I don't belong to the guild. I make good money too, and I don't have to divide up with anyone." He took another drink. "There are not many with as good heads on them as Rapas the Ulsio."

He leaned closer to me. "I like you, Vandor," he said; "you are a good fellow."

His voice was getting thick from drink. "I have one very rich client; he has lots of work, and he pays well. I can get you an odd job with him now and again. Perhaps I can find steady employment for you. How would you like that?"

I shrugged. "A man must live," I said; "he can't be too particular about his job when he hasn't very much money."

"Well, you come along with me; I am going there tonight. While Fal Sivas talks to you, I will tell him that you are just the man that he needs."

"But how about you?" I inquired. "It is your job; certainly no man needs two assassins."

"Never mind about me," said Rapas; "I have other ideas in my head." He stopped suddenly and gave me a quick, suspicious look. It was almost as though what he had said had sobered him. He shook his head, evidently in an effort to clear it.

"What did I say?" he demanded. "I must be getting drunk."

"You said that you had other plans. I suppose you mean that you have a better job in view."

"Is that all I said?" he demanded.

"You said that you would take me to a man called Fal Sivas who would give me employment."

Rapas seemed relieved. "Yes, I will take you to see him tonight."

For the balance of the day Rapas slept, while I occupied my time puttering around my flier in the public hangar on the roof of the hostelry. This was a far more secluded spot than the public sleeping room or the streets of the city, where some accident might pierce my disguise and reveal my identity.

As I worked over my motor, I recalled Rapas's sudden fear that he had revealed something to me in his drunken conversation; and I wondered idly what it might be. It had come following his statement that he had other plans. What plans?

Whatever they were, they were evidently nefarious, or he would not have been so concerned when he feared that he had revealed them.

My short acquaintance with Rapas had convinced me that my first appraisal of his character was correct and that his sobriquet of Rapas the Rat was well deserved.

I chafed under the enforced inactivity of the long day; but at last evening came, and Rapas the Ulsio and I left our quarters and made our way once more to the eating-place.

Rapas was sober now, nor did he take but a single drink with his meal. "You've got to have a clear head when you talk to old Fal Sivas," he said. "By my first ancestor, no shrewder brain was ever hatched of a woman's egg."

After we had eaten, we went out into the night; and Rapas led me through broad avenues and down narrow alleyways until we came to a large building that stood near the eastern wall of Zodanga.

It was a dark and gloomy pile, and the avenue that ran before it was unlighted.

It stood in a district given over to warehouses, and at this time of night its surroundings were deserted.

Rapas approached a small doorway hidden in an angle of a buttress. I saw him groping with his hands at one side of the door, and presently he stepped back and waited.

"Not everyone can gain admission to old Fal Sivas's Place," he remarked, with a tinge of boastfulness. "You have to know the right signal, and that means that you have to be pretty well in the confidence of the old man."

We waited in silence then for perhaps two or three minutes. No sound came from beyond the door; but presently a very small, round port in its surface opened; and in the dim light of the farther moon I saw an eye appraising us. Then a voice spoke.

"Ah, the noble Rapas!" The words were whispered; and following them, the door swung in.

The passage beyond was narrow, and the man who had opened the door flattened himself against the wall that we might pass. Then he closed the door behind us and followed us along a dark corridor, until we finally emerged into a small, dimly lighted room.

Here our guide halted. "The master did not say that you were bringing another with you," he said to Rapas.

"He did not know it," replied Rapas. "In fact, I did not know it myself until today; but it is all right. Your master will be glad to receive him when I have explained why I brought him."

"That is a matter that Fal Sivas will have to decide for himself," replied the slave. "Perhaps you had better go first and speak to him, leaving the stranger here with me."

"Very well, then," agreed my companion. "Remain here until I return, Vandor."

The slave unlocked the door in the far side of the anteroom; and after Rapas had passed through, he followed him and closed it.

It occurred to me that his action was a little strange, as I had just heard him say that he would remain with me, but I would have thought nothing more of the matter had I not presently become impressed with the very definite sensation that I was being watched.

I cannot explain this feeling that I occasionally have. Earth men who should know say that this form of telepathy is scientifically impossible, yet upon many occasions I have definitely sensed this secret surveillance, later to discover that I really was being watched.

As my eyes wandered casually about the room, they came to rest again upon the door beyond which Rapas and the slave had disappeared. They were held momentarily by a small round hole in the paneling and the glint of something that might have been an eye shining in the darkness. I knew that it was an eye.

Just why I should be watched, I did not know; but if my observer hoped to discover anything suspicious about me, he was disappointed; for as soon as I realized that an eye was upon me, I walked to a bench at one side of the room and sat down, instantly determined not to reveal the slightest curiosity concerning my surroundings.

Such surveillance probably meant little in itself, but taken in connection with the gloomy and forbidding appearance of the building and the great stealth and secrecy with which we had been admitted, it crystallized a most unpleasant impression of the place and its master that had already started to form in my mind.

From beyond the walls of the room there came no sound, nor did any of the night noises of the city penetrate to the little anteroom. Thus I sat in utter silence for about ten minutes; then the door opened, and the same slave beckoned to me.

"Follow me," he said. "The master will see you. I am to take you to him."

I followed him along a gloomy corridor and up a winding ramp to the next higher level of the building. A moment later he ushered me into a softly lighted room furnished with Sybaritic luxury, where I saw Rapas standing before a couch on which a man reclined, or I should say, crouched. Somehow he reminded me of a great cat watching its prey, always ready to spring.

"This is Vandor, Fal Sivas," said Rapas, by way of introduction.

I inclined my head in acknowledgment and stood before the man, waiting.

"Rapas has told me about you," said Fal Sivas. "Where are you from?"

"Originally I was from Zodanga," I replied, "but that was years ago before the sacking of the city."

"And where have you been since?" he asked. "Whom have you served?"

"That," I replied, "is a matter of no consequence to anyone but myself. It is sufficient that I have not been in Zodanga, and that I cannot return to the country that I have just fled."

"You have no friends or acquaintances in Zodanga, then?" he asked.

"Of course, some of my acquaintances may still be living; that I do not know," I replied, "but my people and most of my friends were killed at the time that the green hordes overran the city."

"And you have had no intercourse with Zodanga since you left?" he asked.

"None whatsoever."

"Perhaps you are just the man I need. Rapas is sure of it, but I am never sure. No man can be trusted."

"Ah, but master," interrupted Rapas, "have I not always served you well and faithfully?"

I thought I saw a slight sneer curl the lip of Fal Sivas.

"You are a paragon, Rapas," he said, "the soul of honor."

Rapas swelled with importance. He was too egotistical to note the flavor of sarcasm in Fal Sivas's voice.

"And I may consider myself employed?" I asked.

"You understand that you may be called upon to use a dagger more often than a sword," he asked, "and that poisons are sometimes preferred to pistols?"

"I understand."

He looked at me intently.

"There may come a time," he continued, "when you may have to draw your long sword or your short sword in my defense. Are you a capable swordsman?"

"I am a panthan," I replied; "and as panthans live by the sword, the very fact that I am here answers your question."

"Not entirely. I must have a master swordsman. Rapas, here, is handy with the short sword. Let us see what you can do against him."

"To the death?" I asked.

Rapas guffawed loudly. "I did not bring you here to kill you," he said.

"No, not to the death, of course," said Fal Sivas. "Just a short passage. Let us see which one can scratch the other first."

I did not like the idea. I do not ordinarily draw my sword unless I intend to kill, but I realized that I was playing a part and that before I got through I might have to do many things of which I did not approve; so I nodded my assent and waited for Rapas to draw.

His short sword flashed from its scabbard. "I shall not hurt you badly, Vandor," he said; "for I am very fond of you."

I thanked him and drew my own weapon.

Rapas stepped forward to engage me, a confident smile upon his lips. The next instant his weapon was flying across the room. I had disarmed him, and he was at my mercy. He backed away, a sickly grin upon his face. Fal Sivas laughed.

"It was an accident," said Rapas. "I was not ready."

"I am sorry," I told him; "go and recover your weapon."

He got it and came back, and this time he lunged at me viciously. There would have been no mere scratch that time if his thrust had succeeded. He would have spitted me straight through the heart. I parried and stepped in, and again his sword hurtled through the air and clanked against the opposite wall.

Fal Sivas laughed uproariously. Rapas was furious. "That is enough," said the former. "I am satisfied. Sheath your swords."

I knew that I had made an enemy of Rapas; but that did not concern me greatly, since being forewarned I could always be watchful of him. Anyway, I had never trusted him.

"You are prepared to enter my service at once?" asked Fal Sivas.

"I am in your service now," I replied.

He smiled. "I think you are going to make me a good man. Rapas wants to go away for a while to attend to business of his own. While he is away, you will remain here as my bodyguard. When he returns, I may still find use for you in one way or another. The fact that you are unknown in Zodanga may make you very valuable to me." He turned to Rapas. "You may go now, Rapas," he said, "and while you are away, you might take some lessons in swordsmanship."

When Pal Sivas said that, he grinned; but Rapas did not. He looked very sour, and he did not say good-bye to me as he left the room.

"I am afraid that you offended his dignity," said Fal Sivas after the door had closed behind the assassin.

"I shall lose no sleep over it," I replied, "and anyway it was not my fault. It was his."

"What do you mean?" demanded Fal Sivas.

"Rapas is not a good swordsman."

"He is considered an excellent one," Fal Sivas assured me.

"I imagine that as a killer he is more adept with the dagger and poison."

"And how about you?" he asked.

"Naturally, as a fighting man, I prefer the sword," I replied.

Fal Sivas shrugged. "That is a matter of small concern to me," he said. "If you prefer to kill my enemies with a sword, use a sword. All I ask is that you kill them."

"You have many enemies?" I asked.

"There are many who would like to see me put out of the way," he replied. "I am an inventor, and there are those who would steal my inventions. Many of these I have had to destroy. Their people suspect me and seek revenge; but there is one who, above all others, seeks to destroy me. He also is an inventor, and he has employed an agent of the assassins' guild to make away with me.

"This guild is headed by Ur Jan, and he personally has threatened my life because I have employed another than a member of his guild to do my killing."

We talked for a short time, and then Fal Sivas summoned a slave to show me to my quarters. "They are below mine," he said; "if I call, you are to come to me immediately. Good night."

The slave led me to another room on the same level. In fact, to a little suite of three rooms. They were plainly but comfortably furnished.

"Is there anything that you require, master?" the slave inquired, as he turned to leave me.

"Nothing," I replied.

"Tomorrow a slave will be assigned to serve you." With that he left me, and I listened to see if he locked the door from the outside; but he did not, though I would not have been surprised had he done so, so sinister and secretive seemed everything connected with this gloomy pile.

I occupied myself for a few moments inspecting my quarters. They consisted of a living room, two small bedrooms, and a bath. A single door opened from the living room onto the corridor. There were no windows in any of the rooms. There were small ventilators in the floors and in the ceilings, and draughts of air entering the former indicated that the apartment was ventilated mechanically.

The rooms were lighted by radium bulbs similar to those generally used throughout Barsoom.

In the living room was a table, a bench, and several chairs, and a shelf upon which were a number of books. Glancing at some of these, I discovered that they were all scientific works. There were books on medicine, on surgery, chemistry, mechanics, and electricity.

From time to time, I heard what appeared to be stealthy noises in the corridor; but I did not investigate, as I wanted to establish myself in the confidence of Fal Sivas and his people before I ventured to take it upon myself to learn any more than they desired me to know. I did not even know that I wanted to know anything more about the household of Fal Sivas; for, after all, my business in Zodanga had nothing to do with him. I had come to undermine and, if possible, overthrow the strength of Ur Jan and his guild of assassins; and all I needed was a base from which to work. I was, in fact, a little disappointed to find that Fate had thrown me in with those opposed to Ur Jan. I would have preferred and, in fact, had hoped to be able to join Ur Jan's organization, as I felt that I could accomplish much more from the inside than from the out.

If I could join the guild, I could soon learn the identity of its principal members; and that, above all other things, was what I wished to do, that I might either bring them to justice or put the cross upon their hearts with the point of my own sword.

Occupied with these thoughts, I was about to remove my harness and turn into my sleeping silks and furs when I heard sounds of what might have been a scuffle on the level above and then a thud, as of a body falling.

The former preternatural silence of the great house accentuated the significance of the sounds that I was hearing, imparting to them a mystery that I realized might be wholly out of proportion to their true importance. I smiled as I realized the effect that my surroundings seemed to be having upon my ordinarily steady nerves; and had resumed my preparations for the night when a shrill scream rang through the building.

I paused again and listened, and now I distinctly heard the sound of feet running rapidly. They seemed to be approaching, and I guessed that they were coming down the ramp from the level above to the corridor that ran before my quarters.

Perhaps what went on in the house of Fal Sivas was none of my affair, but I have never yet heard a woman scream without investigating; so now I stepped to the door of my living room and threw it open, and as I did so I saw a girl running rapidly toward me. Her hair was disheveled; and from her wide, frightened eyes she cast frequent glances backward over her shoulder.

She was almost upon me before she discovered me; and when she did she paused for a moment with a gasp of astonishment or fear, I could not tell which; then she darted past me through the open door into my living room.

"Close the door," she whispered, her voice tense with suppressed emotion. "Don't let him get me! Don't let him find me!"

No one seemed to be pursuing her, but I closed the door as she had requested and turned toward her for an explanation.

"What is the matter?" I demanded. "From whom were you running?"

"From him." She shuddered. "Oh, he is horrible. Hide me; don't let him get me, please!"

"Whom do you mean? Who is horrible?"

She stood there trembling and wide-eyed, staring past me at the door, like one whom terror had demented.

"Him," she whispered. "Who else could it be?"

"You mean -- -?"

She came close and started to speak; then she hesitated. "But why should I trust you? You are one of his creatures. You are all alike in this terrible place."

She was standing very close to me now, trembling like a leaf. "I cannot stand it!" she cried. "I will not let him!" And then, so quickly that I could not prevent her, she snatched the dagger from my harness and turned it upon herself.

But there I was too quick for her, seizing her wrist before she could carry out her designs.

She was a delicate-looking creature, but her appearance belied her strength.

However, I had little difficulty in disarming her; and then I backed her toward the bench and forced her down upon it.

"Calm yourself," I said; "you have nothing to fear from me -- nothing to fear from anybody while I am with you. Tell me what has happened. Tell me whom you fear."

She sat there staring into my eyes for a long moment, and presently she commenced to regain control of herself. "Yes," she said presently, "perhaps I can trust you. You make me feel that way -- your voice, your looks."

I laid my hand upon her shoulder as one might who would quiet a frightened child. "Do not be afraid," I said; "tell me something of yourself. What is your name?"

"Zanda," she replied.

"You live here?"

"I am a slave, a prisoner,"

"What made you scream?" I asked.

"I did not scream," she replied; "that was another. He tried to get me, but I eluded him, and so he took another. My turn will come. He will get me. He gets us all."

"Who? Who will get you?"

She shuddered as she spoke the name. "Fal Sivas," she said, and there was horror in her tone.

I sat down on the bench beside her and laid my hand on hers. "Quiet yourself," I said; "tell me what all this means. I am a stranger here. I just entered the service of Fal Sivas tonight."

"You know nothing, then, about Fal Sivas?" she demanded.

"Only that he is a wealthy inventor and fears for his life."

"Yes, he is rich; and he is an inventor, but not so great an inventor as he is a murderer and a thief. He steals ideas from other inventors and then has them murdered in order to safeguard what he has stolen. Those who learn too much of his inventions die. They never leave this house. He always has an assassin ready to do his bidding; sometimes here, sometimes out in the city; and he is always afraid of his life.

"Rapas the Ulsio is his assassin now; but they are both afraid of Ur Jan, chief of the guild of assassins; for Ur Jan has learned that Rapas is killing for Fal Sivas for a price far lower than that charged by the guild."

"But what are these wonderful inventions that Fal Sivas works upon?" I asked.

"I do not know all of the things that he does, but there is the ship. That would be wonderful, were it not born of blood and treachery."

"What sort of a ship?" I asked.

"A ship that will travel safely through interplanetary space. He says that in a short time we shall be able to travel back and forth between the planets as easily as we travel now from one city to another."

"Interesting," I said, "and not so very horrible, that I can see."

"But he does other things -- horrible things. One of them is a mechanical brain."

"A mechanical brain?"

"Yes, but of course I cannot explain it. I have so little learning. I have heard him speak of it often, but I do not understand.

"He says that all life, all matter, are the result of mechanical action, not primarily, chemical action. He holds that all chemical action is mechanical.

"Oh, I am probably not explaining it right. It is all so confusing to me, because I do not understand it; but anyway he is working on a mechanical brain, a brain that win think clearly and logically, absolutely uninfluenced by any of the extraneous media that affect human judgments."

"It seems rather a weird idea," I said, "but I can see nothing so horrible about it."

"It is not the idea that is horrible," she said; "it is the method that he employs to perfect his invention. In his effort to duplicate the human brain, he must examine it. For this reason he needs many slaves. A few he buys, but most of them are kidnaped for him."

She commenced to tremble, and her voice came in little broken gasps. "I do not know; I have not really seen it; but they say that he straps his victims so that they cannot move and then removes the skull until he has exposed the brain; and so, by means of rays that penetrate the tissue, he watches the brain function."

"But his victims cannot suffer long," I said; "they would lose consciousness and die quickly."

She shook her head. "No, he has perfected drugs that he injects into their veins so that they remain alive and are conscious for a long time. For long hours he applies various stimuli and watches the reaction of the brain. Imagine if you can, the suffering of his poor victims.

"Many slaves are brought here, but they do not remain long. There are only two doors leading from the building, and there are no windows in the outer walls.

"The slaves that disappear do not leave through either of the two doorways. I see them today; tomorrow they are gone, gone through the little doorway that leads into the room of horror next to Fal Sivas's sleeping quarters.

"Tonight Fal Sivas sent for two of us, another girl and myself. He purposed using only one of us. He always examines a couple and then selects the one that he thinks is the best specimen, but his selection is not determined wholly by scientific requirements. He always selects the more attractive of the girls that are summoned.

"He examined us, and then finally he selected me. I was terrified. I tried to fight him off. He chased me about the room, and then he slipped and fell; and before he could regain his feet, I opened the door and escaped. Then I heard the other girl scream, and I knew that he had seized her, but I have won only a reprieve. He will get me; there is no escape. Neither you nor I will ever leave this place alive."

"What makes you think that?" I inquired.

"No one ever does."

"How about Rapas?" I asked. "He comes and goes apparently as he wishes."

"Yes, Rapas comes and goes. He is Fal Sivas's assassin. He also aids in the kidnaping of new victims. Under the circumstances he would have to be free to leave the building. Then there are a few others, old and trusted retainers, really partners in crime, whose lives Fal Sivas holds in the palm of his hand; but you may rest assured that none of these know too much about his inventions. The moment that one is taken into Fal Sivas's confidence, his days are numbered.

"The man seems to have a mania for talking about his inventions. He must explain them to someone. I think that is because of his great egotism. He loves to boast. That is the reason he tells us who are doomed so much about his work. You may rest assured that Rapas knows nothing of importance. In fact, I have heard Fal Sivas say that one thing that endeared Rapas to him is the assassin's utter stupidity. Fal Sivas says that if he explained every detail of an invention to him, Rapas wouldn't have brains enough to understand it."

By this time the girl had regained control of herself; and as she ceased speaking, she started toward the doorway. "Thank you so much," she said, "for letting me come in here. I shall probably never see you again, but I should like to know who it is who has befriended me."

"My name is Vandor," I replied, "but what makes you think you will never see me again, and where are you going now?"

"I am going back to my quarters to wait for the next summons. It may come tomorrow."

"You are going to stay right here," I replied; "we may find a way of getting you out of this, yet."

She looked at me in surprise and was about to reply when suddenly she cocked her head on one side and listened. "Someone is coming," she said; "they are searching for me."

I took her by the hand and drew her toward the doorway to my sleeping apartment.

"Come in here," I said. "Let's see if we can't hide you."

"No, no," she demurred; "they would kill us both then, if they found me. You have been kind to me. I do not want them to kill you."

"Don't worry about me," I replied; "I can take care of myself. Do as I tell you."

I took her into my room and made her lie down on the little platform that serves in Barsoom. as a bed. Then I threw the sleeping silks and furs over her in a jumbled heap. Only by close examination could anyone have discovered that her little form lay hidden beneath them.

Stepping into the living room, I took a book at random from the shelf; and seating myself in a chair, opened it. I had scarcely done so, when I heard a scratching on the outside of the door leading to the corridor.

"Come in," I called.

The door opened, and Fal Sivas stepped into the room.

Lowering my book, I looked up as Fal Sivas entered. He glanced quickly and suspiciously about the apartment. I had purposely left the door to my sleeping room open, so as not to arouse suspicion should anyone come in to investigate.

The doors to the other sleeping room and bath were also open. Fal Sivas glanced at the book in my hand. "Rather heavy reading for a panthan," he remarked.

I smiled. "I recently read his Theoretical Mechanics. This is an earlier work, I believe, and not quite so authoritative. I was merely glancing through it."

Fal Sivas studied me intently for a moment. "Are you not a little too well educated for your calling?" he asked.

"One may never know too much," I replied.

"One may know too much here," he said, and I recalled what the girl had told me.

His tone changed. "I stopped in to see if everything was all right with you, if you were comfortable."

"Very," I replied.

"You have not been disturbed? No one has been here?"

"The house seems very quiet," I replied. "I heard someone laughing a short time ago, but that was all. It did not disturb me."

"Has anyone come to your quarters?" he asked.

"Why, was someone supposed to come?"

"No one, of course," he said shortly, and then he commenced to question me in an evident effort to ascertain the extent of my mechanical and chemical knowledge.

"I really know little of either subject," I told him. "I am a fighting man by profession, not a scientist. Of course, familiarity with fliers connotes some mechanical knowledge, but after all I am only a tyro."

He was studying me quizzically. "I wish that I knew you better," he said at last; "I wish that I knew that I could trust you. You are an intelligent man. In the matter of brains, I am entirely alone here. I need an assistant. I need such a man as you." He shook his head, rather disgustedly. "But what is the use? I can trust no one."

"You employed me as your bodyguard. For that work I am fitted. Let it go at that."

"You are right," he agreed. "Time will tell what else you are fitted for."

"And if I am to protect you," I continued, "I must know more about your enemies. I must know who they are, and I must learn their plans."

"There are many who would like to see me destroyed, or destroy me themselves; but there is one who, above all others, would profit by my death. He is Gar Nal, the inventor." He looked up at me questioningly.

"I have never heard of him," I said. "You must remember that I have been absent from Zodanga for many years."

He nodded. "I am perfecting a ship that will traverse space. So is Gar Nal. He would like not only to have me destroyed, but also to steal the secrets of my invention that would permit him to perfect his; but Ur Jan is the one I most fear, because Gar Nal has employed him to destroy me."

"I am unknown in Zodanga. I will hunt out this Ur Jan and see what I can learn."

There was one thing that I wanted to learn right then, and that was whether or not Fal Sivas would permit me to leave his house on any pretext.

"You could learn nothing," he said; "their meetings are secret. Even if you could gain admission, which is doubtful, you would be killed before you could get out again."

"Perhaps not," I said; "it is worth trying, anyway. Do you know where they hold their meetings?"

"Yes, but if you want to try that, I will have Rapas guide you to the building."

"If I am to go, I do not want Rapas to know anything about it," I said.

"Why?" he demanded.

"Because I do not trust him," I replied. "I would not trust anyone with knowledge of my plans."

"You are quite right. When you are ready to go, I can give you directions so that you can find their meeting place."

"I will go tomorrow," I said, "after dark."

He nodded his approval. He was standing where he could look directly into the bedroom where the girt was hidden. "Have you plenty of sleeping silks and furs?" he asked.

"Plenty," I replied, "but I will bring my own tomorrow."

"That will not be necessary. I will furnish you all that you require." He still stood staring into that other room. I wondered if he suspected the truth, or if the girl had moved or her breathing were noticeable under the pile of materials beneath which she was hidden.

I did not dare to turn and look for myself for fear of arousing his suspicions further. I just sat there waiting, my hands close to the hilt of my short sword.

Perhaps the girl was near discovery; but, if so, Fal Sivas was also near death that moment.

At last he turned toward the outer doorway. "I will give you directions tomorrow for reaching the headquarters of the gorthans, and also tomorrow I will send you a slave. Do you wish a man or a woman?"

I preferred a man, but I thought that I detected here a possible opportunity for protecting the girl. "A woman," I said.

He smiled. "And a pretty one, eh?"

"I should like to select her myself, if I may."

"As you wish," he replied. "I shall let you look them over tomorrow. May you sleep well."

He left the room and closed the door behind him; but I knew that he stood outside for a long time, listening.

I picked I up the book once more and commenced to read it; but not a word registered on my consciousness, for all my faculties were centered on listening.

After what seemed a long time, I heard him move away; and shortly after I distinctly heard a door close on the level above me. Not until then did I move, but now I arose and went to the door. It was equipped with a heavy bar on the inside, and this I slid silently into its keeper.

Crossing the room, I entered the chamber where the girl lay and threw back the covers that concealed her. She had not moved. As she looked up at me, I placed a finger across my lips.

"You heard?" I asked in a low whisper.

She nodded.

"Tomorrow I will select you as my slave. Perhaps later I shall find a way to liberate you."

"You are kind," she said.

I reached down and took her by the hand. "Come," I said, "into the other room. You can sleep there safely tonight, and in the morning we will plan how we may carry out the rest of our scheme."

"I think that will not be difficult," she said. "Early in the morning everyone but Fal Sivas goes to a large dining room on this level. Many of them will pass along this corridor. I can slip out, unseen, and join them. At breakfast you will have an opportunity of seeing all the slaves. Then you may select me if you still wish to do so."

There were sleeping silks and furs in the room that I had assigned to her, and I knew that she would be comfortable; so I left her, and returning to my own room completed my preparations for the night that had been so strangely interrupted.

Early the next morning Zanda awoke me. "It will soon be time for them to go to breakfast," she said. "You must go before I do, leaving the door open. Then when there is no one in the corridor, I will slip out."

As I left my quarters, I saw two or three people moving along the corridor in the direction that Zanda had told me the dining room lay; and so I followed them, finally entering a large room in which there was a table that would seat about twenty. It was already over half filled. Most of the slaves were women -- young women, and many of them were beautiful.

With the exception of two men, one sitting at either end of the table, all the occupants of the room were without weapons.

The man sitting at the head of the table was the same who had admitted Rapas and me the evening before. I learned later that his name was Hamas, and that he was the major-domo of the establishment.

The other armed man was Phystal. He was in charge of the slaves in the establishment. He also, as I was to learn later, attended to the procuring of many of them, usually by bribery or abduction.

As I entered the room, Hamas discovered me and motioned me to come to him. "You will sit here, next to me, Vandor," he said.

I could not but note the difference in his manner from the night before, when he had seemed more or less an obsequious slave. I gathered that he played two roles for purposes known best to himself or his master. In his present role, he was obviously a person of importance.

"You slept well?" he asked.

"Quite," I replied; "the house seems very quiet and peaceful at night."

He grunted. "If you should hear any unusual sounds at night," he said, "you will not investigate, unless the master or I call you." And then, as though he felt that that needed some explanation, he added, "Fal Sivas sometimes works upon his experiments late at night. You must not disturb him no matter what you may hear."

Some more slaves were entering the room now, and just behind them came Zanda. I glanced at Hamas and saw his eyes narrow as they alighted upon her.

"Here she is now, Phystal," he said.

The man at the far end of the table turned in his seat and looked at the girl approaching from behind him. He was scowling angrily.

"Where were you last night, Zanda?" he demanded, as the girl approached the table.

"I was frightened, and I hid," she replied.

"Where did you hide?" demanded Phystal.

"Ask Hamas," she replied.

Phystal glanced at Hamas. "How should I know where you were?" demanded the latter.

Zanda elevated her arched brows. "Oh, I am sorry," she exclaimed; "I did not know that you cared who knew."

Hamas scowled angrily. "What do you mean by that?" he demanded; "what are you driving at?"

"Oh," she said, "I wouldn't have said anything about it at all but I thought, of course, that Fal Sivas knew."

Phystal was eyeing Hamas suspiciously. All the slaves were looking at him, and you could almost read their thoughts in the expressions on their faces.

Hamas was furious, Phystal suspicious; and all the time the girl stood there with the most innocent and angelic expression on her face.

"What do you mean by saying such a thing?" shouted Hamas.

"What did I say?" she asked, innocently.

"You said -- you said-"

"I just said, 'ask Hamas.' Is there anything wrong in that?"

"But what do I know about it?" demanded the majordomo.

Zanda shrugged her slim shoulders. "I am afraid to say anything more. I do not want to get you in trouble."

"Perhaps the less said about it, the better," said Phystal.

Hamas started to speak, but evidently thought better of it. He glowered at Zanda for a moment and then fell to eating his breakfast.

Just before the meal was over, I told Hamas that Fal Sivas had instructed me to select a slave.

"Yes, he told me," replied the major-domo. "See Phystal about it; he is in charge of the slaves."

"But does he know that Fal Sivas gave me permission to select anyone that I chose?"

"I will tell him."

A moment later he finished his breakfast; and as he was leaving the dining room, he paused and spoke to Phystal.

Seeing that Phystal also was about ready to leave the table, I went to him and told him that I would like to select a slave.

"Which one do you want?" he asked.

I glanced around the table, apparently examining each of the slaves carefully until at last my eyes rested upon Zanda.

"I will take this one," I said.

Phystal's brows contracted, and he hesitated.

"Fal Sivas said that I might select whomever I wished," I reminded him.

"But why do you want this one?" he demanded.

"She seems intelligent, and she is good-looking," I replied. "She will do as well as another until I am better acquainted here." And so it was that Zanda was appointed to serve me. Her duties would consist of keeping my apartments clean, running errands for me, cleaning my harness, shining my metal, sharpening my swords and daggers, and otherwise making herself useful.

I would much rather have had a man slave, but events had so ordered themselves that I had been forced into the role of the girl's protector, and this seemed the only plan by which I could accomplish anything along that line; but whether or not Fal Sivas would permit me to keep her, I did not know. That was a contingency which remained for future solution when, and if, it eventuated.

I took Zanda back to my quarters; and while she was busying herself with her duties there, I received a call summoning me to Fal Sivas.

A slave led me to the same room in which Fal Sivas had received Rapas and me the night before, and as I entered the old inventor greeted me with a nod. I expected him to immediately question me concerning Zanda, for both Hamas and Phystal were with him; and I had no doubt but that they had reported all that had occurred at the breakfast table.

However, I was agreeably disappointed, for he did not mention the incident at all, but merely gave me instructions as to my duties.

I was to remain on duty in the corridor outside his door and accompany him when he left the room. I was to permit no one to enter the room, other than Hamas or Phystal, without obtaining permission from Fal Sivas. When he left the room, I was to accompany him. Under no circumstances was I ever to go to the level above, except with his permission or by his express command. He was very insistent in impressing this point upon my mind; and though I am not overly curious, I must admit that now that I had been forbidden to go to any of the levels above, I wanted to do so.

"When you have been in my service longer and I know you better," explained Fal Sivas, "I hope to be able to trust you; but for the present you are on probation."

That was the longest day I have ever spent, just standing around outside that door, doing nothing; but at last it drew to a close, and when I had the opportunity, I reminded Fal Sivas that he had promised to direct me to Ur Jan's headquarters, so that I might try to gain entrance to them that night.

He gave me very accurate directions to a building in another quarter of the city.

"You are free to start whenever you wish," he said, in conclusion; "I have given Hamas instructions that you may come and go as you please. He will furnish you with a pass signal whereby you may gain admission to the house. I wish you luck," he said, "but I think that the best you will get will be a sword through your heart. You are pitting yourself against the fiercest and most unscrupulous gang of men in Zodanga."

"It is a chance that I shall have to take," I said. "Good night."

I went to my quarters and told Zanda to lock herself in after I had left and to open the door only in answer to a certain signal which I imparted to her. She was only too glad to obey my injunction.

When I was ready to leave the building, Hamas conducted me to the outer doorway.

Here he showed me a hidden button set in the masonry and explained to me how I might use it to announce my return.

I had gone but a short distance from the house of Fal Sivas when I met Rapas the Ulsio. He seemed to have forgotten his anger toward me, or else he was dissimulating, for he greeted me cordially.

"Where to?" he asked.

"Off for the evening," I replied.

"Where are you going, and what are you going to do?"

"I am going to the public house to get my things together and store them, and then I shall look around for a little entertainment."

"Suppose we get together later in the evening," he suggested.

"All right," I replied; "when and where?"

"I will be through with my business about half after the eighth zode. Suppose we meet at the eating-place I took you to yesterday."

"All right," I said, "but do not wait long for me. I may get tired of looking for pleasure and return to my quarters long before that."

After leaving Rapas, I went to the public house where I had left my things; and gathering them up I took them to the hangar on the roof and stored them in my flier. This done, I returned to the street and made my way toward the address that Fal Sivas had given me.

The way led me through a brilliantly lighted shopping district and into a gloomy section of the old town. It was a residential district, but of the meaner sort.

Some of the houses still rested upon the ground, but most of them were elevated on their steel shafts twenty or thirty feet above the pavement.

I heard laughter and song and occasional brawling -- the sounds of the night life of a great Martian city, and then I passed on into another and seemingly deserted quarter.

I was approaching the headquarters of the assassins. I kept in the shadows of the buildings, and I avoided the few people that were upon the avenue by slipping into doorways and alleys. I did not wish anyone to see me here who might be able afterward to recognize or identify me. I was playing a game with Death, and I must give him no advantage.

When finally I reached the building for which I was seeking, I found a doorway on the opposite side of the avenue from which I could observe my goal without being seen.

The farther moon cast a faint light upon the face of the building but revealed to me nothing of importance.

At first, I could discern no lights in the building; but after closer observation I saw a dim reflection behind the windows of the upper floor. There, doubtless, was the meeting-place of the assassins; but how was I to reach it?

That the doors to the building would be securely locked and every approach to the meeting-place well guarded, seemed a foregone conclusion.

There were balconies before the windows at several levels, and I noticed particularly that there were three of these in front of windows on the upper story. These balconies offered me a means of ingress to the upper floor if I could but reach them.

The great strength and agility which the lesser gravitation of Mars imparts to my earthly muscles might have sufficed to permit me to climb the exterior of the building, except for the fact that this particular building seemed to offer no foothold up to the fifth story, above which its carved ornamentation commenced.

Mentally debating every possibility, by a process of elimination, I was forced to the conclusion that my best approach would be by way of the roof.

However, I determined to investigate the possibilities of the main entrance on the ground floor; and was about to cross the avenue for that purpose when I saw two men approaching. Stepping back into the shadows of my hiding-place, I waited for them to pass; but instead of doing so they stopped before the entrance to the building I was watching. They were there but a moment when I saw the door open and the men admitted. This incident convinced me that someone was on guard at the main entrance to the building, and that it would be futile for me to attempt to enter there.

There now remained to me only the roof as a means of entrance to the building, and I quickly decided upon a plan to accomplish my design.

Leaving my hiding-place, I quickly retraced my steps to the public house in which I had been lodging, and went immediately to the hangar on the roof.

The place was deserted, and I was soon at the controls of my flier. I had now to run the chance of being stopped by a patrol boat, but this was a more or less remote contingency; as, except in cases of public emergency, little attention is paid to private fliers within the walls of the city.

However, to be on the safe side, I flew low, following dark avenues below the level of the roof tops; and in a short time I reached the vicinity of the building that was my goal.

Here I rose above the level of the roofs and, having located the building, settled gently to its roof.

The building had not been intended for this purpose, and there was neither hangar nor mooring rings; but there are seldom high winds on Mars, and this was a particularly quiet and windless night.

Leaving the deck of the flier, I searched the roof for some means of ingress to the building. I found a single small scuttle, but it was strongly secured from within, and I could not budge it -- at least without making far too much noise.

Going to the edge of the building, overlooking the avenue, I looked down upon one of the balconies directly below me. I could have lowered myself from the eaves and, hanging by my hands, dropped directly onto it; but here again I faced the danger of attracting attention by the noise that I must make in alighting.

I examined the face of the building just below me and discovered that, in common with most Martian buildings, the carved ornamentation offered handholds and footholds sufficient to my need.

Slipping quietly over the eaves, I felt around with my toes until I found a projection that would support me. Then, releasing one hand, I felt for a new hold; and so, very slowly and carefully, I descended to the balcony.

I had selected the place of my descent so that I was opposite an unlighted window. For a moment I stood there listening. Somewhere within the interior of the building I heard subdued voices. Then I threw a leg over the sill and entered the darkness of the apartment beyond.

Slowly I groped my way to a wall and then followed along it until I came to a door at the end of the room opposite the window. Stealthily I felt for the latch and lifted it. I pulled gently; the door was not locked; it swung in toward me without noise.

Beyond the door was a corridor. It was very faintly illuminated, as though by reflected light from an open doorway or from another corridor. Now the sound of voices was more distinct. Silently I crept in the direction from which they came.

Presently I came to another corridor running at right angles to the one I was following. The light was stronger here, and I saw that it came from an open doorway farther along the corridor which I was about to enter. I was sure, however, that the voices did not come from this room that I could see, as they would have been far more clear and distinct had they.

My position was a precarious one. I knew nothing at all about the interior arrangements of the building. I did not know along which corridor its inmates came and went. If I were to approach the open doorway, I might place myself in a position where discovery would be certain.

I knew that I was dealing with killers, expert swordsmen all; and I did not try to deceive myself into believing that I would be any match for a dozen or more of them.

However, men who live by the sword are not unaccustomed to taking chances, sometimes far more desperate chances than their mission may seem to warrant.

Perhaps such was the case now, but I had come to Zodanga to learn what I could about the guild of assassins headed by the notorious Ur Jan; and now that fortune had placed me in a position where I might gain a great deal of useful information, I had no thought of retreating because a little danger confronted me.

Stealthily I crept forward, and at last I reached the door. Very cautiously I surveyed the interior of the room beyond, as I moved, inch by inch, across the doorway.

It was a small room, evidently an anteroom; and it was untenanted. There was some furniture in it -- a table, some benches; and I noticed particularly an old-fashioned cupboard that stood diagonally across one corner of the room, one of its sides about a foot from the wall.

From where I stood in the doorway, I could now hear the voices quite distinctly; and I was confident that the men I sought were in the adjoining room just beyond.

I crept into the anteroom and approached the door at the opposite end. Just to the left of the door was the cupboard that I have mentioned.

I placed my car close to the panels of the door in an effort to overhear what was being said in the room beyond, but the words came to me indistinct and muffled. This would never do. I could neither see nor hear anything under these conditions.

I decided that I must find some other point of approach and was turning to leave the room when I beard footsteps approaching along the corridor. I was trapped!

On more than one occasion in my life have I been in tight places, but it seemed to me at the time that I had seldom before blundered into such a trap. The footsteps were approaching rapidly along the corridor. I could tell by their sound that they were made by more than one person.

If there were only two men, I might fight my way past them; but the noise of the encounter would attract those in the room behind me, and certainly any sort of a fight whatever would delay me long enough so that those who were attracted by it would be upon me before I could escape.

Escape! How could I escape if I were detected? Even if I could reach the balcony, they would be directly behind me; and I could not climb out of reach toward the roof before they could drag me down.

My position seemed rather hopeless, and then my eye fell upon the cupboard standing in the corner just beside me and the little foot wide crack between it and the wall.

The footsteps were almost opposite the doorway. There was no time to be lost.

Quickly I slipped behind the cupboard and waited.

Nor was I a moment too soon. The men in the corridor turned into the room almost immediately, so soon, in fact, that it seemed to me that they must have seen me; but evidently they had not, for they crossed directly to the door to the inner chamber, which one of them threw open.

From my hiding place I could see this man plainly and also into the room beyond, while the shadow of the cupboard hid me from detection.

What I saw beyond that door gave me something to think about. There was a large room in the center of which was a great table, around which were seated at least fifty men -- fifty of the toughest looking customers that I have ever seen gathered together. At the head of the table was a huge man whom I knew at once to be Ur Jan. He was a very large man, but well proportioned; and I could tell at a glance that he must be a most formidable fighter.

The man who had thrown open the door I could see also, but I could not see his companion or companions as they were hidden from me by the cupboard.

Ur Jan had looked up as the door opened. "What now?" he demanded. "Who have you with you?" and then, "Oh, I recognize him."

"He has a message for you, Ur Jan," said the man at the door. "He said it was a most urgent message, or I would not have brought him here."

"Let him come in," said Ur Jan. "We will see what he wants, and you return to your post."

"Go on in," said the man, turning to his companion behind him, "and pray to your first ancestor that your message interests Ur Jan; as otherwise you will not come out of that room again on your own feet."

He stood aside and I saw a man pass him and enter the room. It was Rapas the Rat.

Just seeing his back as he approached Ur Jan told me that he was nervous and terrified. I wondered what could have brought him here, for it was evident that he was not one of the guild. The same question evidently puzzled Ur Jan, as his next words indicated.

"What does Rapas the Ulsio want here?" he demanded.

"I have come as a friend," replied Rapas. "I have brought word to Ur Jan that he has long wanted."

"The best word that you could bring to me would be that someone had slit your dirty throat," growled Ur Jan.

Rapas laughed -- it was a rather weak and nervous laugh.

"The great Ur Jan likes his little joke," mumbled Rapas meekly.

The brute at the head of the table leaped to his feet and brought his clenched fist down heavily upon the solid sorapus wood top.

"What makes you think I joke, you miserable little slit throat? But you had better laugh while you can, for if you haven't some important word for me, if you have come here where it is forbidden that outsiders come, if you have interrupted this meeting for no good reason, I'll put a new mouth in your throat; but you won't be able to laugh through it."

"I just wanted to do you a favor," pleaded Rapas. "I was sure that you would like to have the information that I bring, or I would not have come."

"Well, quick! out with it, what is it?"

"I know who does Fal Sivas's killing."

Ur Jan laughed. It was rather a nasty laugh. "So do I" he bellowed; "it is Rapas the Ulsio."

"No, no, Ur Jan," cried Rapas, "you wrong me. Listen, Ur Jan."

"You have been seen entering and leaving the house of Fal Sivas," accused the assassin chief. "You are in his employ; and for what purpose would he employ such as you, unless it was to do his killing for him?"

"Yes, I went to the house of Fal Sivas. I went there often. He employed me as his bodyguard, but I only took the position so that I might spy upon him. Now that I have learned what I went there to learn, I have come straight to you."

"Well, what did you learn?"

"I have told you. I have learned who does his killing."

"Well, who is it, if it isn't you?"

"He has in his employ a stranger to Zodanga -- a panthan named Vandor. It is this man who does the killing."

I could not repress a smile. Every man thinks that he is a great character reader; and when something like this occurs to substantiate his belief, he has reason to be pleased; and the more so because few men are really good judges of character, and it is therefore very seldom that one of us is open to self congratulation on this score.

I had never trusted Rapas, and from the first I had set him down as a sneak and a traitor. Evidently he was all these.

Ur Jan glowered at him skeptically. "And why do you bring me this information? You are not my friend. You are not one of my people, and as far as I know you are the friend of none of us."

"But I wish to be," begged Rapas. "I risked my life to get this information for you because I want to join the guild and serve under the great Ur Jan. If that came to pass, it would be the proudest day of my life. Ur Jan is the greatest man in Zodanga -- he is the greatest man on all Barsoom. I want to serve him, and I will serve him faithfully."

All men are susceptible to flattery, and oftentimes the more ignorant they are, the more susceptible. Ur Jan was no exception. One could almost see him preening himself. He squared his great shoulders and threw out his chest.

"Well," he said in a milder voice, "we'll think it over. Perhaps we can use you, but first you will have to arrange it so that we can dispose of this Vandor." He glanced quickly around the table. "Do any of you men know him?"

There was a chorus of denials -- no one admitted to knowing me.

"I can point him out to you," said Rapas the Ulsio. "I can point him out this very night."

"What makes you think so?" asked Ur Jan.

"Because I have an engagement to meet him later on at an eating place that he frequents."

"Not a bad idea," said Ur Jan. "At what time is this meeting?"

"About half after the eighth zode," replied Rapas.

Ur Jan glanced quickly around the table. "Uldak," he said, "you go with Rapas; and don't return while this Vandor still lives."

I got a good look at Uldak as Ur Jan singled him out; and as I watched him come toward the door with Rapas on his way to kill me, I fixed every detail of the man's outward appearance indelibly upon my mind, even to his carriage as he walked; and though I saw him for but a moment then, I knew that I should never forget him.

As the two men left the larger chamber and crossed the anteroom in which I was concealed, Rapas explained to his companion the plan that he had in mind.

"I will take you now and show you the location of the eating place in which I am to meet him. Then you can return later and you will know that the man who is with me is the man whom you seek."

I could not but smile as the two men turned into the corridor and passed out of earshot. What would they and Ur Jan have thought, had they known that the object of their criminal purpose was within a few yards of them?

I wanted to follow Rapas and Uldak, for I had a plan that it would have been amusing to carry out; but I could not escape from behind the cupboard without passing directly in front of the doorway leading into the room where sat Ur Jan and his fifty assassins.

It looked as though I would have to wait until the meeting ended and the company had dispersed before I could make my way to the roof and my flier.

Although I was inclined to chafe at the thought of this enforced inactivity, I nevertheless took advantage of the open door to familiarize myself with the faces of all of the assassins that I could see. Some of them sat with their backs toward me, but even these occasionally revealed a glimpse of a profile.

It was fortunate that I took early advantage of this opportunity to implant the faces of my enemies upon my memory, for but a moment or two after Rapas and Uldak had left the room, Ur Jan looked up and noticed the open door and directed one of the assassins sitting near it to close it.

Scarcely had the lock clicked when I was out from behind the cupboard and into the corridor.

I saw no one and heard no sound in the direction that the assassins had used in coming into and going from the anteroom; and as my way led in the opposite direction, I had little fear of being apprehended. I moved rapidly toward the apartment through the window of which I had entered the building, as the success of the plan I had in mind depended upon my being able to reach the eating place ahead of Rapas and Uldak.

I reached the balcony and clambered to the roof of the building without mishap, and very shortly thereafter I was running my flier into the hangar on the roof of the public house where I stored it. Descending to the street, I made my way to the vicinity of the eating place to which Rapas was conducting Uldak, reasonably certain that I should arrive there before that precious pair.

I found a place where I could watch the entrance in comparative safety from discovery, and there I waited. My vigil was not of long duration, for presently I saw the two approaching. They stopped at the intersection of two avenues a short distance from the place, and after Rapas had pointed it out to Uldak, the two separated, Rapas continuing on in the direction of the public house where I had first met him, while Uldak turned back into the avenue along which they had come from the rendezvous of the assassins.

It still lacked half a zode of the time that I was to meet Rapas, and for the moment at least I was not concerned with him -- my business was with Uldak.

As soon as Rapas had passed me upon the opposite side of the street, I came out of my hiding place and walked rapidly in the direction that Uldak had taken.

As I reached the intersection of the two streets, I saw the assassin a little distance ahead of me. He was walking slowly, evidently merely killing time until he might be certain that the hour had arrived when I was to meet Rapas at the eating place.

Keeping to the opposite side of the street, I followed the man for a considerable distance until he entered a quarter that seemed to be deserted -- I did not wish an audience for what I was about to do.

Crossing the avenue, I increased my gait; and the distance between us rapidly lessened until I was but a few paces behind him. I had moved very quietly, and he was not aware that anyone was near him. Only a few paces separated us when I spoke.

"You are looking for me?" I inquired.

He wheeled instantly, and his right hand flew to the hilt of his sword. He eyed me narrowly. "Who are you?" he demanded.

"Perhaps I have made a mistake," I said; "you are Uldak, are you not?"

"What of it?" he demanded.

I shrugged. "Nothing much, except that I understand that you have been sent to kill me. My name is Vandor."

As I ceased speaking, I whipped out my sword. He looked utterly astonished as I announced my identity, but there was nothing for him to do but defend himself, and as he drew his weapon he gave a nasty little laugh.

"You must be a fool," he said. "Anyone who is not a fool would run away and hide if he knew that Uldak was looking for him."

Evidently the man thought himself a great swordsman. I might have confused him by revealing my identity to him, for it might take the heart out of any Barsoomian warrior to know that he was facing John Carter; but I did not tell him. I merely engaged him and felt him out for a moment to ascertain if he could make good his boast.

He was, indeed, an excellent swordsman and, as I had expected, tricky and entirely unscrupulous. Most of these assassins are entirely without honor; they are merely killers.

At the very first he fought fairly enough because he thought that he could easily overcome me; but when he saw that he could not, he tried various shady expedients and finally he attempted the unpardonable thing with his free hand, he sought to draw his pistol.

Knowing his kind, I had naturally expected something of the sort; and in the instant that his fingers closed upon the butt of the weapon I struck his sword aside and brought the point of my own heavily upon his left wrist, nearly severing his hand.

With a scream of rage and pain, he fell back; and then I was upon him in earnest.

He yelled for mercy now and cried that he was not Uldak; that I had made a mistake, and begged me to let him go. Then the coward turned to flee, and I was forced to do that which I most disliked to do; but if I were to carry out my plan I could not let him live, and so I leaped close and ran my sword through his heart from behind.

Uldak lay dead upon his face.

As I drew my sword from his body, I looked quickly about me. No one was within sight. I turned the man over upon his back and with the point of my sword made a cross upon his breast above his heart.

Rapas was waiting for me when I entered the eating-place. He looked very self-satisfied and contented.

"You are right on time," he said. "Did you find anything to amuse you in the night life of Zodanga?"

"Yes," I assured him. "I enjoyed myself immensely. And you?"

"I spent a most profitable evening. I made excellent connections; and, my dear Vandor, I did not forget you."

"How nice of you," I said.

"Yes, you shall have reason to remember this evening as long as you live," he exclaimed, and then he burst into laughter.

"You must tell me about it," I said.

"No, not now," he replied, "It must remain a secret for a time. You will know all about it soon enough, and now let us eat. It is my treat tonight. I shall pay for everything."

The miserable rat of a man seemed to have swelled with importance now that he felt himself almost a full-fledged member of Ur Jan's guild of assassins.

"Very well," I said, "this shall be your treat," for I thought it would add to my enjoyment of the joke to let the poor fool foot the bill, and to make it still more amusing I ordered the most expensive dishes that I could find.

When I had entered the eating-place, Rapas had already seated himself facing the entrance; and he was continually glancing at it. Whenever anyone entered, I could see the look of expectation on his face change to one of disappointment.

We spoke of various unimportant things as we ate; and as the meal progressed, I could not but note his growing impatience and concern.

"What is the matter, Rapas?" I inquired after a while. "You seem suddenly nervous. You are always watching the entrance. Are you expecting someone?"

He got himself in hand then, very quickly; but he cast a single searching glance at me through narrowed lids. "No, no," he said, "I was expecting no one; but I have enemies. It is always necessary for me to be watchful."

His explanation was plausible enough, though I knew of course that it was not the right one. I could have told him that he was watching for someone who would never come, but I did not.

Rapas dragged the meal out as long as he could, and the later it grew, the more nervous he became and the more often his glance remained upon the entrance. At last I made a move to go, but he detained me. "Let us stop a little longer," he said. "You are in no hurry, are you?"

"I should be getting back," I replied. "Fal Sivas may require my services."

"No," he told me, "not before morning."

"But I must have some sleep," I insisted.

"You will get plenty of sleep," he said; "don't worry."

"Well, if I am going to, I had better start for bed," I said, and with that I arose.

He tried to detain me, but I had extracted about all the pleasure out of the evening that I thought it held for me, and so I insisted upon leaving.

Reluctantly he arose from the table. "I will walk a little way with you," he said.

We were near the door leading to the avenue when two men entered. They were discussing something rather excitedly as they greeted the proprietor.

"The Warlord's agents are at work again," said one of them.

"How is that?" asked the proprietor.

"They have just found the body of one of Ur Jan's assassins in the Avenue of the Green Throat -- the cross of the Warlord was above his heart."

"More power to the Warlord," said the proprietor. "Zodanga would be better off if we were rid of all of them."

"By what name was the dead man known?" asked Rapas, with considerable more concern, I imagine, than he would have cared to reveal.

"Why, some man in the crowd said that he believed his name was Uldak," replied one of the two men who had brought the news.

Rapas paled.

"Was he a friend of yours, Rapas?" I asked.

The Ulsio started. "Oh, no," he said. "I did not know him. Let us be going."

Together we walked out into the avenue and started in the direction of the House of Fal Sivas. We walked shoulder to shoulder through the lighted district near the eating-place. Rapas was very quiet and seemed nervous. I watched him out of the comer of my eye and tried to read his mind, but he was on guard and had closed it against me.

Oftentimes I have an advantage over Martians in that I can read their minds, though they can never read mine. Why that is, I do not know. Mind reading is a very commonplace accomplishment on Mars, but to safeguard themselves against its dangers, all Martians have cultivated the ability to close their minds to others at will -- a defense mechanism of such long standing as to have become almost a universal characteristic; so that only occasionally can one be caught off his guard.

As we entered the darker avenues, however, it became apparent that Rapas was trying to drop behind me; and then I did not have to read his mind to know what was in it -- Uldak had failed, and now The Rat had an opportunity to cover himself with glory and win the esteem of Ur Jan by carrying out the assignment of Uldak.

If a man has a sense of humor, a situation such as this can be very enjoyable, as, indeed, it was to me. Here I was walking along a dark avenue with a man who intended to murder me at the first opportunity, and it was necessary for me to thwart his plans without letting him know that I suspected them; for I did not want to kill Rapas the Ulsio, at least not at present. I felt that I could make use of him in one way or another without his ever suspecting that he was aiding me.

"Come," I said, at last, "why do you lag? Are you getting tired?" And I linked my left arm through his sword arm, and thus we continued on toward the house of Fal Sivas.

After a short distance, at the intersection of two avenues, Rapas disengaged himself. "I am leaving you here," he said; "I am not going back to the house of Fal Sivas tonight."

"Very well, my friend," I said; "but I shall be seeing you soon again, I hope."

"Yes," he replied, "soon."

"Tomorrow night, possibly," I suggested, "or if not tomorrow night, the night after. Whenever I am at liberty, I shall come to the eating-house; and perhaps I shall find you there."

"Very well," he said; "I eat there every night."

"May you sleep well, Rapas."

"May you sleep well, Vandor." Then he turned into the avenue at our left, and I proceeded on my way.

I thought that he might follow me, but he did not, and so I came at last to the house of Fal Sivas.

Hamas admitted me, and after passing a few words with him I went directly to my quarters where, in answer to my signal, Zanda admitted me.

The girl told me that the house had been very quiet during the night, and that no one had disturbed her or attempted to enter our quarters. She had prepared my sleeping silks and furs; and, as I was rather tired, I soon sought them.

Immediately after breakfast the next morning, I went on duty again at the door of Fal Sivas's study. I had been there but a short time when he summoned me to his person.

"What of last night?" he asked. "What luck did you have? I see that you are here alive; so I take it that you did not succeed in reaching the meeting-place of the assassins."

"On the contrary, I did," I told him. "I was in the room next to them and saw them all."

"What did you learn?"

"Not much. When the door was closed, I could hear nothing. It was open only a short time."

"What did you hear while it was open?" he asked.

"They knew that you had employed me as your body guard."

"What!" he demanded. "How could they have known that?"

I shook my head. "There must be a leak," I told him.

"A traitor!" he exclaimed.

I did not tell him about Rapas. I was afraid that he would have him killed, and I did not want him killed while he might be of use to me.

"What else did you hear?" he demanded.

"Ur Jan ordered that I be killed."

"You must be careful," said Fal Sivas. "Perhaps you had better not go out again at night."

"I can take care of myself," I replied, "and I can be of more service if I can get about at night and talk to people on the outside than I can by remaining cooped up here when I am off duty."

He nodded. "I guess you are right," he said, and then for a moment he sat in deep thought. Finally he raised his head. "I have it!" he exclaimed. "I know who the traitor is."

"Yes?" I asked politely.

"It is Rapas the Ulsio -- Ulsio! He is well named."

"You are sure?" I asked.

"It could be no one else," replied Fal Sivas emphatically. "No one else has left the premises but you two since you came. But we will put an end to that as soon as he returns. When he comes back, you will destroy him. Do you understand?"

I nodded.

"It is a command," he said; "see that it is obeyed." For some time he sat in silence, and I could see that he was studying me intently. At last he spoke.

"You have a smattering of the sciences I judge from the fact of your interest in the books in your quarters."

"Only a smattering," I assured him.

"I need such a man as you," he said, "if I could only find someone whom I might trust. But who can one trust?" He seemed to be thinking aloud. "I am seldom wrong," he continued musingly. "I read Rapas like a book. I knew that he was mean and ignorant and at heart a traitor."

He wheeled suddenly upon me. "But you are different. I believe that I can take a chance with you, but if you fail me-" he stood up and faced me, and I never saw such a malevolent expression upon a human face before. "If you fail me, Vandor, you shall die such a death as only the mind of Fal Sivas can conceive."

I could not help but smile. "I can die but once," I said.

"But you can be a long time at the dying, if it is done scientifically." But now he had relaxed, and his tone was a little bantering. I could imagine that Fal Sivas might enjoy seeing an enemy die horribly.

"I am going to take you into my confidence -- a little just a little," he said.

"Remember that I have not asked it," I replied, "that I have not sought to learn any of your secrets."

"The risk will be mutual," he said, "your life against my secrets. Come, I have something to show you."

He led me from the room, along the corridor past my quarters, and up the ramp to the forbidden level above. Here we passed through a magnificently appointed suite of living quarters and then through a little door hidden behind hangings, and came at last into an enormous loft that extended upward to the roof of the building, evidently several levels above us.

Supported by scaffolding and occupying nearly the entire length of the enormous chamber, was the strangest looking craft that I have ever seen. The nose was ellipsoidal; and from the greatest diameter of the craft, which was just back of the nose, it sloped gradually to a point at the stem.

"There it is," said Fal Sivas, proudly; "the work of a lifetime, and almost completed."

"An entirely new type of ship," I commented. "In what respect is it superior to present types?"

"It is built to achieve results that no other ship can achieve," replied Fal Sivas. "It is designed to attain speed beyond the wildest imaginings of man. It will travel routes that no man or ship has ever traveled.

"In that craft, Vandor, I can visit Thuria and Cluros. I can travel the far reaches of space to other planets."

"Marvellous," I said.

"But that is not all. You see that it is built for speed. I can assure you that it is built to withstand the most terrific pressure, that it is insulated against the extremes of heat and cold. Perhaps, Vandor, other inventors could have accomplished the same end. In fact, I believe Gar Nal has already done so, but there is only one man upon Barsoom, doubtless there is only one brain in the entire Solar System, that could have done what Fal Sivas has done. I have given that seemingly insensate mechanism a brain with which to think. I have perfected my mechanical brain, Vandor, and with just a little more time, just a few refinements, I can send this ship out alone; and it will go where I wish it to go and come back again.

"Doubtless, you think that impossible. You think Fal Sivas is mad; but look! Watch closely."

He centered his gaze upon the nose of the strange-looking craft, and presently I saw it rise slowly from its scaffolding for about ten feet and hang there poised in mid-air. Then it elevated its nose a few feet, and then its tail, and finally it settled again and rested evenly upon its scaffolding.

I was certainly astonished. Never in all my life had I seen anything so marvellous, nor did I seek to hide my admiration from Fal Sivas.

"You see," he said, "I did not even have to speak to it. The mechanical mind that I have installed in the ship responds to thought waves. I merely have to impart to it the impulse of the thought that I wish it to act upon. The mechanical brain then functions precisely as my brain would, and directs the mechanism that operates the craft precisely as the brain of the pilot would direct his hand to move levers, press buttons, open or close throttles.

"Vandor, it has been a long and terrible battle that I have had to wage to perfect this marvellous mechanism. I have been compelled to do things which would revolt the finer sensibilities of mankind; but I believe that it has all been well worthwhile. I believe that my greatest achievement warrants all that it has cost in lives and suffering.

"I, too, have paid a price. It has taken something out of me that can never be replaced. I believe, Vandor, that it has robbed me of every human instinct. Except that I am mortal, I am as much a creature of cold insensate formulas as that thing which you see resting there before you. Sometimes, because of that, I hate it; and yet I would die for it. I would see others die for it, countless others, in the future, as I have in the past. It must live. It is the greatest achievement of the human mind."

Every one of us, I believe, is possessed of two characters. Oftentimes they are so much alike that this duality is not noticeable, but again there is a divergence so great that we have the phenomenon of a Dr. Jekyll and Mr. Hyde in a single individual. The brief illuminating self-revealment of Fal Sivas suggested that he might be an example of such wide divergence in character.

He seemed immediately to regret this emotional outburst and turned again to an explanation of his invention.

"Would you like to see the inside of it?" he asked.

"Very much," I replied.

He concentrated his attention again upon the nose of the ship, and presently a door in its side opened and a rope ladder was lowered to the floor of the room.

It was an uncanny procedure -- just as though ghostly hands had performed the work.

Fal Sivas motioned me to precede him up the ladder. It was a habit of his to see that no one ever got behind him that bespoke the nervous strain under which he lived, always in fear of assassination.

The doorway led directly into a small, comfortably, even luxuriously furnished cabin.

"The stem is devoted to storerooms where food may be carried for long voyages," explained Fal Sivas. "Also aft are the motors, the oxygen and water-generating machines, and the temperature-regulating plant. Forward is the control room. I believe that that will interest you greatly," and he motioned me to precede him through a small door in the forward bulkhead of the cabin.

The interior of the control room, which occupied the entire nose of the ship, was a mass of intricate mechanical and electrical devices.

On either side of the nose were two large, round ports in which were securely set thick slabs of crystal.

From the exterior of the ship these two ports appeared like the huge eyes of some gigantic monster; and, in truth, this was the purpose they served.

Fal Sivas called my attention to a small, round metal object about the size of a large grapefruit that was fastened securely just above and between the two eyes.

From it ran a large cable composed of a vast number of very small insulated wires. I could see that some of these wires connected with the many devices in the control room, and that others were carried through conduits to the after part of the craft.

Fal Sivas reached up and laid a hand almost affectionately upon the spherical object to which he had called my attention. "This," he said, "is the brain."

Then he called my attention to two spots, one in the exact center of each crystal of the forward ports. I had not noticed them at first, but now I saw that they were ground differently from the balance of the crystals.

"These lenses," explained Fal Sivas, "focus upon this aperture in the lower part of the brain," and he called my attention to a small hole at the base of the sphere, "that they may transmit to the brain what the eyes of the ship see. The brain then functions mechanically precisely as the human brain does, except with greater accuracy."

"It is incredible!" I exclaimed.

"But, nevertheless, true," he replied. "In one respect, however, the brain lacks human power. It cannot originate thoughts. Perhaps that is just as well, for could it, I might have loosed upon myself and Barsoom an insensate monster that could wreak incalculable havoc before it could be destroyed, for this ship is equipped with high-power radium rifles which the brain has the power to discharge with far more deadly accuracy than may be achieved by man."

"I saw no rifles," I said.

"No," he replied. "They are encased in the bulkheads, and nothing of them is visible except small round holes in the hull of the ship. But, as I was saying, the one weakness of the mechanical brain is the very thing that makes it so effective for the use of man. Before it can function, it must be charged by human thought-waves. In other words, I must project into the mechanism the originating thoughts that are the food for its functioning.

"For example, I charge it with the thought that it is to rise straight up ten feet, pause there for a couple of seconds, and then come to rest again upon its scaffolding.

"To carry the idea into a more complex domain, I might impart to it the actuating thought that it is to travel to Thuria, seek a suitable landing place, and come to the ground. I could carry this idea even further, warning it that if it were attacked it should repel its enemies with rifle fire and maneuver so as to avoid disaster, returning immediately to Barsoom, rather than suffer destruction.

"It is also equipped with cameras, with which I could instruct it to take pictures while it was on the surface of Thuria."

"And you think it will do these things, Fal Sivas?" I asked.

He growled at me impatiently. "Of course it will. Just a few more days and I will have the last detail perfected. It is a minor matter of motor gearing with which I am not wholly satisfied."

"Perhaps I can help you there," I said. "I have learned several tricks in gearing during my long life in the air."

He became immediately interested and directed me to return to the floor of his hangar. He followed me down, and presently we were pouring over the drawings of his motor.

I soon found what was wrong with it and how it might be improved. Fal Sivas was delighted. He immediately recognized the value of the points I had made.

"Come with me," he said; "we will start work on these changes at once."

He led me to a door at one end of the hangar and, throwing it open, followed me into the room beyond.

Here, and in a series of adjoining rooms, I saw the most marvellously equipped mechanical and electrical shops that I have ever seen; and I saw something else, something that made me shudder as I considered the malignity of this man's abnormal obsession for secrecy in the development of his inventions.

The shops were well manned by mechanics, and every one of them was manacled to his bench or to his machine. Their complexions were pasty from long confinement, and in their eyes was the hopelessness of despair.

Fal Sivas must have noted the expression upon my face; for he said quite suddenly, and apropos of nothing else than my own thoughts, "I have to do it, Vandor; I cannot take the risk of one of them escaping and revealing my secrets to the world before I am ready."

"And when will that time come?" I asked.

"Never," he exclaimed, with a snarl. "When Fal Sivas dies, his secrets die with him. While he lives, they will make him the most powerful man in the universe. Why, even John Carter, Warlord of Mars, will have to bend the knee to Fal Sivas."

"And these poor devils, then, will remain here all their lives?" I asked.

"They should be proud and happy," he said, "for are they not dedicating themselves to the most glorious achievement that the mind of man has ever conceived?"

"There is nothing, Fal Sivas, more glorious than freedom," I told him.

"Keep your silly sentimentalism to yourself," he snapped. "There is no place for sentiment in the house of Fal Sivas. If you are to be of value to me, you must think only of the goal, forgetting the means whereby we attain it."

Well, I saw that I could accomplish nothing for myself or his poor victims by antagonizing him, and so I deferred with a shrug. "Of course, you are right, Fal Sivas," I agreed.

"That is better," he said, and then he called a foreman and together we explained the changes that were to be made in the motor.

As we turned away and left the chamber, Fal Sivas sighed. "Ah," he said, "if I could but produce my mechanical brain in quantities. I could do away with all these stupid humans. One brain in each room could perform all the operations that it now takes from five to twenty men to perform and perform them better, too -- much better."

Fal Sivas went to his laboratory on the same level then, and told me that he would not require me for a while but that I should remain in my quarters and keep the door open, seeing that no unauthorized person passed along the corridor toward the ramp leading to his laboratories.

When I reached my quarters, I found Zanda polishing the metal on an extra set of harness that she said Fal Sivas had sent to me for my use.

"I was talking with Hamas's slave a little while ago," she remarked, presently.

"She says that Hamas is worried about you."

"And why?" I asked.

"He thinks that the master has taken a fancy to you, and he fears for his own authority. He has been a very powerful man here for many years."

I laughed. "I don't aspire to his laurels," I told her.

"But he does not know that," said Zanda. "He would not believe it, if he were told. He is your enemy and a very powerful enemy. I just wanted to warn you."

"Thanks, Zanda," I said. "I shall be watchful of him, but I have a great many enemies; and I am so accustomed to having them that another, more or less, makes little difference to me."

"Hamas may make a great difference to you," she said. "He has the ear of Fal Sivas. I am so worried about you, Vandor."

"You mustn't worry; but if it will make you feel any better, do not forget that you have the ear of Hamas through his slave. You can let her know that I have no ambition to displace Hamas."

"That is a good idea," she said, "but I am afraid that it will not accomplish much; and if I were you, the next time I went out of the building, I should not return. You went last night, so I suppose that you are free to come and go as you will."

"Yes," I replied, "I am."

"Just as long as Fal Sivas does not take you to the floor above and reveal any of his secrets to you, you will probably be allowed to go out, unless Hamas makes it a point to prevail upon Fal Sivas to take that privilege away from you."

"But I have already been to the level above," I said, "and I have seen many of the wonders of Fal Sivas's inventions."

She gave little cry of alarm, then. "Oh, Vandor, you are lost!" she cried. "Now you will never leave this terrible place."

"On the contrary, I shall leave it tonight, Zanda," I told her. "Fal Sivas has agreed that I should do so."

She shook her head. "I cannot understand it," she said, "and I shall not believe it until after you have gone."

Toward evening Fal Sivas sent for me. He said that he wanted to talk to me about some further changes in the gearing of the motor, and so I did not get out that night, and the next day he had me in the shops directing the mechanics who were working on the new gears, and again he made it impossible for me to leave the premises.

In one way or another, he prevented it night after night; and though he didn't actually refuse permission, I began to feel that I was, indeed, a prisoner.

However, I was much interested in the work in the shops and did not mind much whether I went out or not.

Ever since I had seen Fal Sivas's wonder-craft and had listened to his explanation of the marvellous mechanical brain that controlled it, it had been constantly in my thoughts. I saw in it all the possibilities of power for good or evil that Fal Sivas had visualized, and I was intrigued by the thought of what the man who controlled it could accomplish.

If that man had the welfare of humanity at heart, his invention might prove a priceless boon to Barsoom; but I feared that Fal Sivas was too selfish and too mad for power to use his invention solely for the public good.

Such meditation naturally led me to wonder if another than Fal Sivas could control the brain. The speculation intrigued me, and I determined to ascertain at the first opportunity if the insensate thing would respond to my will.

That afternoon Fal Sivas was in his laboratory, and I was working in the shops with the poor manacled artisans. The great ship lay in the adjoining room. Now, I thought, presented as good a time as any to make my experiment.

The creatures in the room with me were all slaves. Furthermore, they hated Fal Sivas; so it made no difference to them what I did.

I had been kind to them and had even encouraged them to hope, though they could not believe that there was any hope. They had seen too many of their number die in their chains to permit them to entertain a thought of escape. They were apathetic in all matters, and I doubt that any of them noticed when I left the shop and entered the hangar where the ship rested upon its scaffolding.

Closing the door behind me, I approached the nose of the craft and focused my thoughts upon the brain within. I imparted to it the will to rise from its scaffolding as I had seen Fal Sivas cause it to do and then to settle down again in its place. I thought that if I could cause it to do that, I could cause it to do anything that Fal Sivas could.

I am not easily excited; but I must confess that my every nerve was tense as I watched that great thing above me, wondering if it would respond to those invisible thought-waves that I was projecting into it.

Concentrating thus upon this one thing naturally curtailed the other activities of my mind, but even so I had visions of what I might accomplish if my experiment proved successful.

I presume that I had been there but a moment, yet it seemed a long while; and then slowly the great craft rose as though lifted by an invisible hand. It hovered for a moment ten feet above its scaffolding, and then it settled down to rest again.

As it did so, I heard a noise behind me; and, turning quickly, I saw Fal Sivas standing in the doorway of the shop.

Nonchalance is a corollary of poise. I was thankful at that moment that the poise gene of some ancient forebear had been preserved in my line and handed down to me. Whether or not Fal Sivas had entered the room before the ship came to rest again upon its scaffolding, I did not know. If not, he had only missed the sight by a matter of a split second. My best momentary defense was to act on the assumption that he had not seen, and this I determined to do.

Standing there in the doorway, the old inventor was eyeing me sternly. "What are you doing in here?" he demanded.

"The invention fascinates me; it intrigues my imagination," I replied. "I stepped in from the shop to have another look at it. You had not told me that I should not do so."

He knitted his brows in thought. "Perhaps, I didn't," he said at last; "but I tell you now. No one is supposed to enter this room, unless by my express command."

"I will bear that in mind," I said.

"It will be well for you if you do, Vandor."

I walked then toward the door where he stood, with the intention of returning to the shop; but Fal Sivas barred my way.

"Wait a moment," he said, "perhaps you have been wondering if the brain would respond to your thought-impulses."

"Frankly, I have," I replied.

I wondered how much he knew, how much he had seen. Perhaps he was playing with me, secure in his own knowledge; or perhaps he was merely suspicious and was seeking confirmation of his suspicion. However that might be, I was determined not to be trapped out of my assumption that he had not seen and did not know.

"You were not, by any chance, attempting to see if it would respond?" he asked.

"Who, other than a stupid dolt, once having seen this invention, would not naturally harbor such a thought?" I asked.

"Quite right, quite right," he admitted; "it would only be natural, but did you succeed?" The pupils of his eyes contracted; his lids narrowed to two ominous slits. He seemed to be trying to bore into my soul; and, unquestionably, he was attempting to read my mind; but that, I knew, he could not accomplish.

I waved my hand in the direction of the ship. "Has it moved?" I asked with a laugh.

I thought that I saw just a faint hint of