Creaking along the dank, filthy corridors, metal rods piercing her skin, down to her brittle bones, the creature the terrified children call "The Mechanical Girl" roams in the shadows. When Amy (Calista Flockhart) arrives at the remote, dilapidated Mercy falls Children's Hospital to replace a nurse who left shortly before, she finds the patients have been the victims of a number of inexplicable attacks. Amy befriends Maggie, a child who says she has been speaking to "Charlotte", a mechanical girl she believes lives on the second floor that has been closed for forty years. Whatever is happening at Mercy Falls, Amy knows the despicable figure lurking on the floor above them holds the answers.