After escaping from a psychiatric hospital, bipolar patient Sybil Foster (Joanne Froggatt) is forced to fend for herself by conning unsuspecting hotel guests into letting her share their room. Things work out relatively well until one of her targets turns up dead and the police suspect Sybil is to blame. But because of her fractured mind, Sybil can't be sure if she's the one who actually committed the crime ...