For Karigan G'ladheon, the call of magic in her blood is too strong to resist. Karigan returns to the Green Riders, the magical messengers of the king, to find she's badly needed. Rider magic has become unstable, many Riders have been lost, and the Rider corps is seriously threatened.

The timing couldn't be worse. An ancient evil, long dormant, has reawakened, and the world is in peril. Karigan must face deadly danger and complex magic to save the kingdom from certain doom.

With the ghostly help of the First Rider, Karigan had managed to drive off the spirit of Mornhavon—but for how long, no one could know. The descendants of those Arcosians are ready to strike, reaching out to claim the land their forebears had tried to conquer. Worse, these vengeful enemies had spent generations honing their powers of dark magic—a force against which the Sacoridians had no defense.