While on his way to meet Jane returning from England, Tarzan  rescues an Amazon from a black panther. Jane arrives accompanied Sir Guy Henderson's archeological expedition. The scientists have recognized the bracelet worn by Jane as being of the design associated with a fabled Amazon society rumoured to exist in a hidden African valley. Tarzan refuses to help them but Boy, believing that he is aiding the cause of civilization, leads them to the secret valley of the Palyrians. The safari is captured by the Amazons but the Amazon that Tarzan had rescued agrees to help Boy and the party escapes. They proceed to loot the tribe's treasure chamber where Henderson is accidentally killed and the Amazon is stabbed, but is able to alarm the other Amazons before she dies. The woman warriors kill most of the party. They recapture Boy and sentence him to death. Cheetah reports to Tarzan who leaves the two surviving safari members to die in quicksand. He returns the stolen treasure in exchange for Boy's freedom.