Upon returning from Greece, Tom, his master the Spook, and Alice find the County under siege. The Spook's home and library have been destroyed, prompting them to seek refuge on the island of Mona. There, they encounter a twisted Shaman and a more formidable enemy: Bony Lizzie, a powerful witch who has escaped from the Spook's bonds. With the aid of a buggane—a creature that steals life force—Lizzie aims to claim the island as her own and establish herself as a Witch Queen.