A British army squadron patrols the African jungle on a rendezvous with Tarzan and Jane. They are visited by Boy (Tarzan Jr. the new king of the jungle), and the faithful Cheetah. The British commander urges Tarzan to seek safety in the Fort while Cuban Mercenaries raid the jungle looking for spoils. Tarzan refuses and the British leave, promising to return soon. Jane sends Boy to gather food, and while he is swimming in the river Boy is attacked by a killer crocodile. They fight. In victory, Boy gives the famous 'Tarzan Yell'. Meanwhile, the Cuban Mercenaries capture Tarzan and Jane, leaving a ransom note attached to a tree. Cheetah is with them, but he gets away. Cheetah finds Boy and communicates the situation. Boy swings through the jungle and finds the Cuban camp. Boy uses the famous 'Tarzan Yell' to demoralize his enemies. Then ... He attacks. In the ensuing battle, Boy fights the Cubans with a rope lasso, with a bow and arrow, with a machete, and with his bare hands. Finally, with Cheetah's help, the Cubans are defeated. Just as the battle ends, the British squadron arrives to take care of things. The tranquility of the jungle is restored.