Whyborne, Griffin, and their friends have faced down cultists, monsters, and sorcerers. But their greatest challenge is now upon them. On the return voyage from Balefire Manor, Whyborne receives the worst news possible: Widdershins has fallen before the onslaught of the Fideles and their servants. There’s still time to stop the return of the Masters, but that window grows shorter by the hour. Together with Christine and Iskander, Whyborne and Griffin must reach Widdershins to face the ultimate test—and decide the fate of the world, once and for all.