On the first night in their new home, Nora and her son are besieged by unusual intruders – they appear on camera, but not to the naked eye. This leads Nora to discover the home’s security system is one of a kind; it was built to detect ghosts. But when she tries to use the system to defend against them, it gets turned against her, locking her inside with the uncanny trespassers. Now she must confront the sinister history of the house, and her connection to it, if she’s to save her son and escape.