After accidentally hitting a gray cat on a dark road, a lonely woman named Ellen brings it home, determined to save it. But when the animal revives in impossible ways and begins feeding on her blood, Ellen’s guilt curdles into attachment. As her body deteriorates and a mutilated stranger appears at her door with desperate warnings, Ellen is forced to confront the terrifying truth: the cat is not a helpless creature at all, but something older, parasitic, and deeply patient. Trapped inside her own house and her own unraveling mind, Ellen must decide whether to destroy the thing she rescued or surrender to the twisted comfort it offers.