John Gregory, who is a seventh son of a seventh son and also the local spook, has protected the country from witches, boggarts, ghouls and all manner of things that go bump in the night. However John is not young anymore, and has been seeking an apprentice to carry on his trade. Most have failed to survive. The last hope is a young farmer's son named Thomas Ward. Will he survive the training to become the spook that so many others couldn't? When Mother Malkin, the queen of evil witches, escapes the pit she was imprisoned in by professional monster hunter Spook decades ago and kills his apprentice, he recruits young Tom, the seventh son of the seventh son, to help him.