Brave explorers led by the last Druid, Walker Boh, traveled across unknown seas in search of an elusive magic. But not it seems that Walker and his team were lured there for sinister, unforeseen purposes. As the crew abroad the airship Jerle Shannara is being attacked by evil forces, the Druids protégé, Bek Rowe, and his companions are being pursued by the mysterious Isle Witch. Meanwhile, Walker is alone, caught in a dark maze beneath the ruined city of Castletown, stalked by a hungry, unseen enemy. It is alive, but not human, coveting the magic of Druids, elves, even the Ilse Witch. It hunts men for its own designs. It is Antrax: a spirit that feeds of enchantment and traps the souls of men. And with hit, the fate of the Four Lands hangs in the balance.