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… ?