In the city of Lovecraft, the Proctors rule and a great Engine turns below the streets, grinding any resistance to their order to dust. The necrovirus is blamed for Lovecraft's epidemic of madness, for the strange and eldritch creatures that roam the streets after dark, and for everything that the city leaders deem Heretical — born of the belief in magic and witchcraft. And for Aoife Grayson, her time is growing shorter by the day. Aoife Grayson's family is unique, in the worst way — every one of them, including her mother and her elder brother Conrad, has gone mad on their 16th birthday. And now, a ward of the state, and one of the only female students at the School of Engines, she is trying to pretend that her fate can be different

Everything Aoife thought she knew about the world was a lie. There is no Necrovirus. And Aoife isn't going to succomb to madness because of a latent strain — she will lose her faculties because she is allergic to iron. Aoife isn't human. She is a changeling — half human and half from the land of Thorn. And time is running out for her. When Aoife destroyed the Lovecraft engine she released the monsters from the Thorn Lands into the Iron Lands and now she must find a way to seal the gates and reverse the destruction she's ravaged on the world that's about to poison her

Aoife Grayson must face death to win back Dean — the love who was ripped from the Iron Lands of the living when he was shot in the arctic north. But getting to the Deadlands is something that Aoife can't do on her own. And if she can find a way there, Tremaine would surely never allow it. He has sworn to keep her in the Thorn Lands, the fairie home of her mother, Nerissa. But Aoife is determined to find her way out. And she has no trouble if that means she has to kill Tremain and his queen to do it.