Olive is seeing ghosts. A spectral, robed figure is haunting the Academy, Olive in particular, appearing to her and giving sinister instructions.

Olive Silverlock is possessed by the spirit of her ancestor, Amity Arkham, a ghoulish entity who wants to burn Gotham City to the ground. As Amity leads Olive on a mission of fire and vengeance, the rest of Detective Club scrambles to find a way to free their friend.

"Gotham City's most prestigious prep school is a very weird place. It's got a spooky campus, oddball teachers, and rich benefactors always dropping by...like that weirdo Bruce Wayne. But nothing is as strange as the students! Like, what's up with Olive Silverlock? Is she crazy or what? Where did she go last summer? And what's the deal with her creepy mom? And how come that Freshman Maps is always following her around? And is she still going out with...