Apprentice Tom and the Spook for whom he works flee to Ireland, where a powerful witch has joined forces with the dark mages trying to call forth ancient powers to destroy Tom.

Tom is dismayed when his master the Spook decrees that they will be spending the winter on gloomy and forbidding Anglezarke Moor but soon discovers the reason for his master's decision, as they tangle with two dangerous witches and struggle to keep a dark mage from resurrecting an ancient evil.

Provides insights into the life of Grimalkin, one of the deadliest witches in the country, if not the world, whose uneasy truce with the Spook's apprentice, Tom, unites them against the ultimate evil of the Fiend.

Returning from Greece, Tom and the Spook find that their home, including the Spook's precious library of knowledge, has been burned to the ground, and that their battle against the denizens of the dark must continue.

As sixty-year-old John Gregory reflects on the past, he reveals how the world of ghosts, ghasts, witches, and boggarts was exposed to him and he later became the Spook, even though his first intention had been to join the priesthood.