Bobby Pendragon is a seemingly normal boy who is catapulted into the middle of an immense, interdimensional conflict full of danger and discovery. His success or failure will ultimately decide the course of human existence.

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.

With Saint Dane seemingly on the verge of toppling all of the territories, Pendragon and Courtney set out to rescue Mark and find themselves traveling--and battling--their way through different worlds as they try to save all of Halla.

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

Fourteen-year-old Bobby Pendragon, having learned he is a Traveler--someone who can ride "flumes" through time and space, is soon off to the alternative dimension of Denduron where he teams up with Loor, a girl his age from the warrior-territory of Zadaa, in an attempt to save the gentle Milago people from slavery.