English bwanas wind their way through uncharted territory toward the homeland of the hostile Wazuri. There, they hope to lay hands on diamonds they say are needed for Britain's armaments. But the entire safari is a ruse. It's leaders are jewel thieves who've duped Tarzan into being their guide. The Ape-Man has a fierce fight on his hands in this fourth Tarzan film starring Lex Barker.