Travelers near Zambezi are being killed, apparently by leopards. The commissioner (Dennis Hoey) asks Tarzan to look into the matter. Tarzan immediately doubts that leopards are the problem. At the same time, Tarzan, Jane Porter (Tarzan), and Boy take in Kimba, a boy who claims to have become lost in the jungle. Kimba Tommy Cook (actor) is the brother of Queen Lea, leader of a leopard cult. She has dispatched him to spy on Tarzan. Queen Lea also conspires with Ameer Lazar (Edgar Barrier), a Western-educated doctor who resents the West's domination of the area.