The Nightmare Garden (2012)(The second book in the Iron Codex series)

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.