Young Tom, the seventh son of a seventh son, starts work as an apprentice for the village spook, whose job is to protect ordinary folk from "ghouls, boggarts, and all manner of wicked beasties."

When witches steal Tom's inheritance and kidnap his relatives, Tom, the Spook, and Alice set out for Pendle Hill, a particularly dangerous district, in hopes of preventing the three witch clans from uniting to raise the Fiend, the Devil himself, thus bringing about an age of darkness.

Tom is reunited with his mother and must return to Greece to face a new and terrible threat from the dark forces, and a momentous decision must be made, causing a serious rift between Tom and the Spook that threatens to separate them forever.

The Spook and his apprentice, Thomas Ward, have been successful in ridding the county of witches, ghosts, and boggarts, but they face a much more formidable task when they travel to Priestown to confront the Bane and the Quisitor.

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.

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.