After successfully protecting his village from Soltra, Tom leaves his family to embark on a dangerous quest through the desert to battle Vipero the Snake Man.

A strange force has been creeping over the plains of Avantia. The animals are stampeding, and brush fires sweep the prairie. The cattlemen are spooked -whispers of a mysterious horseman are spreading as fast as the stampedes. And now that someone has disappeared on a cattle drive, suspicion runs high. Tom and Elenna speed to the plains to stop Tagus the Night Horse before he can do any more damage. But Tom soon finds himself mistakenly thrown in jail....