Spooks protect the County from the supernatural—witches, boggarts, ghasts, and ghosts—they fight the Dark. This trade is dark, literally, and infinitely dangerous. And it only seems to be getting worse as the Dark is starting to gain power whilst John Gregory's own is only fading. As the Spook discovers his new apprentice's unsettling abilities and true lineage—the fact that she is currently both a being of the Dark and the Light—can he be the one to guide her to the side of the Light at her most impressionable? Or will she fall into the Dark and become the most dangerous thing the County has faced since the prime of the Pendle Witches?