After three long years away, Thomas Elliot, a crippled war-hero, returns home expecting a heartfelt reunion with his beloved wife, Bonnie. However, their reunion takes an unexpected turn when Bonnie fails to recognise him. Thomas soon comes to realise that Bonnie's life now revolves entirely around serving a sinister stray cat that has taken up residence in their house. As Bonnie commits bizarre and horrific acts in service of the stray, Thomas desperately tries to reconnect with her. Pushed to the brink of madness, Thomas soon comes to realise he is up against something far greater, older, and darker than he had ever imagined.