 Dr.Brooks (E.Alyn Warren) is captured by followers of Zar, God of the Jeweled Fingers, but he is soon rescued from their lost city by Tarzan (Buster Crabbe), a while man who was raised in the jungle by apes and speaks no English to speak of.But Tarzan undertakes to locate Brooks  daughter Mary (Julie Bishop as Jacqueline Wells)after seeing a photograph of her. Meanwhile, back in the jungle,Mary and Bob Hall (Edward Woods) are searching for her father. Their guides, Jeff (Philo McCullough) and Nick (Mathew Betz), are more interested in finding the treasure of Zar and scoring with Mary than finding Dr.Brooks. Jeff is in the possession of a message offering a large reward for Tarzan---dead or alive. A group of Arabs, also captivated by Mary, accompany the searchers. Following a series of plots and counterplots, foiled by Tarzan, all hands are eventually captured by the followers of Zar. Jeff and Nick are killed and the survivors promise never to return to the Lost City. Mary decides to remain in the jungle as she has become quite fond of quaffing grapes in a cave with Tarzan.