For years, Old Gregory has been the Spook for the county, ridding the local villages of evil. Now his time is coming to an end. But who will take over for him? Twenty-nine apprentices have tried—some floundered, some fled, some failed to stay alive.

Only Thomas Ward is left. He's the last hope; the last apprentice.

Can Thomas succeed? Will he learn the difference between a benign witch and a malevolent one? Does the Spook's warning against girls with pointy shoes include Alice? And what will happen if Thomas accidentally frees Mother Malkin, the most evil witch in the county ... ?