Tarzan becomes concerned when news reaches him of plans to build a dam in a geologically unsound area. He needs to prove the weakness in the plan and why none of the government surveys in the area have not uncovered the same issues.
A doctor trying to control an outbreak of disease among the tribes is wanted for murder. Tarzan intervenes to allow the doctor to complete his work before being taken into custody. Tarzan is concerned however that the charges against the man may not be all they seem to be.
Tarzan takes a boat to escort a convicted killer, Velasquez, to the authorities. Also on the boat is the wife of a man the killer's band is holding for ransom. She forces Tarzan at gunpoint to escort her with Velasquez to his camp where her husband is being held. She has left the ransom money hidden behind, but Jai and Cheetah find it.
After the village is burned and Tarzan, Jai, the chief, and numerous villagers are captured by the slavers, General Bertram and Charity must work together despite their differences. Tarzan escapes his captors and comes to their aid. He decides to follow behind the slavers to discover who is leading them.
After poacher and arsonist Dan Burton escapes from custody, Tarzan tracks him and his adoring girlfriend to an oceanside cliff, and a fateful encounter. But Burton's girlfriend and two henchmen later track Tarzan down and force him to lead them back to the scene.
Trina MacKenzie, one of seven girls on an expedition, is also trying to find her uncle, who she believes to be doing humanitarian work. She finds that he has become the leader of a large tribe, and has helped them develop more peaceful ways. But Tarzan comes to believe that his latest crusade, involving a statue he claims to be obtaining but which locals insist does not exist, may involve less than noble intentions.
Alex Spence, a world judo champion, is also a braggart who wants to prove he can best Tarzan in any physical endeavor. This rivalry is being taken advantage of by a band of ruthless smugglers, whose diminutive leader wants to steal a huge golden idol and use Alex's boat to hijack it out of the country. To achieve this goal he also kidnaps Alex's girlfriend.