When he finds a powerful crystal, Professor George Challenger gains the powers of a God, putting himself and the other explorers in great danger.

Veronica and Malone are captured by an angry mob who need slaves to mine their quarry. They soon discover that their fellow prisoners are not human; they are machines who are helping aliens repair their spaceship. Will the aliens discover that our heroes are human?!

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.

When a lost archaeological expedition discovers a mysterious burial urn, the young student who opens it suddenly collapses in convulsions. Though she quickly recovers, Professor Hamilton, the expedition's leader, suspects she's contracted a disease from the urn's skeletal remains. He believes that's the only rational explanation for the inscription on the urn, warning that an evil demon is imprisoned within.

But the next day, Roxton and Marguerite discover the expedition's camp has been torn apart, and that of all the archaeologists only two survive-Hamilton and his rival, Professor Campbell. In a tense standoff, the two men claim the other is possessed by the demon. Roxton's and Marguerite's intervention only succeeds in making the archaeologists suspect the demon has jumped into one of the two explorers.