When Iris was a teen, her twin sister Piper was kidnapped.Now an adult, Iris wants one thing - proof. And if the police still won't help, she'll just have to find it her own way: by interning at the isolated Shoal Island Hospital for the criminally insane, where secrets lurk in the shadows and are kept under lock and key.But Iris soon realizes that something even more sinister is simmering beneath the surface of the Shoal, and that the patients aren't the only ones being observed...