When troubled nurse Amy arrives at the dilapidated Mercy Falls Children’s Hospital to help its evacuation she discovers that the patients have been disturbed by a hostile presence. Children's bones are being inexplicably broken; they are nervous and afraid. Of something intangible, invisible. Something full of pain and hatred. Something that shouldn't even exist… Amy knows the perpetrator must be found to reveal the truth. And the truth is darker and more sinister than anyone could ever suspect.