In his ongoing battle to save Earth and its parallel worlds from the demon Saint Dane, fifteen-year-old Bobby Pendragon travels to Veelox, a world whose inhabitants have abandoned their real lives in favor of virtual reality.

While Pendragon is trapped on Ibara, Alder returns to Denduron and reluctantly goes into battle again, and other Travelers face obstacles of various sorts, Saint Dane gains the power he seeks on Second Earth and makes his push to destroy and rebuild Halla.

Fourteen-year-old Bobby Pendragon is not like other boys his age. His uncle Press is a Traveler, and, as Bobby has learned, that means Uncle Press is responsible, through his journeys, for solving interdimensional conflict wherever he encounters it. His mission is nothing less than to save the universe from ultimate evil. And heś taking Bobby along for the ride.

Each of the Travelers returns home to learn the truth about their origins before being reunited for a final, ineveitable confrontation with Saint Dane, whose efforts to control Halla are destroying its very foundations.

"They came from the sky parachuting out of military helicopters to invade Tucker Pierce's idyllic hometown on Pemberwick Island, Maine. They call themselves SYLO and they are a secret branch of the U.S. Navy. SYLO's commander, Captain Granger, informs Pemberwick residents that the island has been hit by a lethal virus and must be quarantined. Now Pemberwick is cut off from the outside world. Tucker believes there's more to SYLO's story. He was on...

Having escaped from Pemberwick Island, Kent, Tori, Olivia, and Tucker continue to try to get word out about SYLO, the organization that had quarantined them, while trying to avoid being caught in the middle of an inexplicable new civil war.

Once again, Tucker Pierce and friends must fight for their lives against the better-equipped SYLO, and they will risk nearly everything to keep each other safe the battle's climax nears.

While Pendragon is trapped on Ibara, Alder returns to Denduron and reluctantly goes into battle again, and other Travelers face obstacles of various sorts, Saint Dane gains the power he seeks on Second Earth and makes his push to destroy and rebuild Halla.

Taking advantage of a severe drought and the long-standing distrust between two tribes, the demonic Saint Dane attempts to take over Loor's home planet of Zadaa, opposed once again by the teenaged Pendragon and other Travelers.

Cooper Foley, who has a knack for getting into trouble, ends up in the middle of a border war between the worlds of the living and the dead, trying to find out about the mysterious Morpheus Road.