When Roxton is running from a tyrannosaur, the earth suddenly swallows him up; the party follows a river to an underground ocean.

Stung by a giant bee, Summerlee lies near death; Challenger seeks a way to repel an attack by the ape-men.

Challenger, Malone and Marguerite find a subterranean civilization after being trapped in an abandoned mine.

Roxton changes the lives of the Tintas when he kills a warrior from the Hikari tribe; a World War I flying ace crashes in the jungle and takes Marguerite, Malone and Summerlee as prisoners.

After slapping a young king, Marguerite must choose between instant death or marrying the boy.

Veronica reunites with her father; the team must fight Kartas, a bounty hunter after Veronica's father.

A dying Roxton makes an evil pact to regain his life and save Marguerite.

The friends emerge from battle to find that one of their number is lost, and goons have enslaved a village.

Roxton saves a young woman and steps right into Balar's trap.

Dinosaurs are behaving oddly, but the crew knows something is really wrong when Marguerite is nice to everyone.

Danielle crafts a voodoo doll of Roxton, putting him in her control.

Werewolves make life a nightmare in the treehouse; Challenger faces a scientific challenge when Malone turns beastly.

Hoping to end starvation, Challenger becomes the first human subject to test his new experimental substitute for food. But his nutritional beverage is not as successful for him as it was for his lab mice, and he quickly becomes obsessed with discovering the reason why. Then obsession leads to madness as Challenger is confronted by two opposing hallucinations. The first is a vision of himself as a young, driven scientist. The second is his beloved wife, Jessie, as he left her in London three years earlier. Unconscious and near death, Challenger is finally discovered by his friends. But will their limited medical knowledge be enough to reverse the ravages of his experiment, without placing him in even greater peril?

Two days before Challenger's latest attempt to leave the Plateau by balloon, Veronica and Finn encounter a strange phenomenon and are briefly transported into the post-apocalyptic future of New Amazonia. Soon after, Roxton finds himself being chased by 17th-century Conquistadors while Marguerite is captured by Druids determined to sacrifice her in order to avert a mysterious storm which is fast approaching.

As different planes of reality continue to collide, Veronica at last realizes the time has come for her to fulfill her destiny as Protector and wield her mother's pendant-the Trion. But even as she prepares to sacrifice her life to save her friends, she does not know if she's made the right decision-for once the power of the Trion is unleashed, will it save the Plateau, or destroy it… ?