After centuries of undisturbed slumber, the Stoor Worm—the World Eater—is waking. A creature of monstrous proportions and unimaginable evil, the Worm must be destroyed. Already its murderous hatchlings are spreading terror and destruction. And a strange trio—Mad Sweeney the Fool, Alexia the Maiden, and the Obby Oss, a two-legged, talking horse—are trying to convince one ordinary boy that he alone can save the world.