A band of adventures sets off to prove the existence of dinosaurs deep in the forest of the Amazon. After an unfortunate accident leaves them stranded, they must put their trust in a jungle girl to save them from the dangerous predators on the plateau.

Marguerite makes a deal with a local chieftain to get off the Plateau. The deal is to hand over Veronica to the chief for marriage, something she wants no part of. Like all such schemes, things don't work out as planned and the team must fight a variety of threats in order to save the chiefs daughter, Veronica's virtue, and their own necks.

Challenger and Marguerite discover an ancient Temple whose entrance is guarded by a carving of three armed warriors. When Marguerite falls into a pit of spikes, Challenger must leave her, to get help. As he leaves, the Guardians come to life. While Marguerite lies bleeding, she hallucinates. As Challenger is returning with the others, the Guardians attack them with invincible strength, but stop suddenly when they see Malone bleeding from a chest wound. While Veronica takes Malone home, the others hurry to the temple. When Roxton and Challenger reach her, Marguerite is baffled when they can see her hallucination, Adrienne. Following Adrienne's claims there is an exit from the plateau via the Temple, Challenger follows her map to the Temple's altar where he is confronted by William Maple White, a dead colleague whose journals had led him to the Lost World.