Successful couple Marianne and Jacques live in a large Paris apartment with their two children, Julien and Aude. When a mysterious older couple called the Worms knock on their front door, claiming to have lived there years earlier, Marianne invites them in. The Worms are eccentric but seemingly harmless. Yet, soon after their visit, mysterious things start to occur. Doors lock themselves, the children act strangely and their babysitter Daphnee kills herself. As Marianne and Jacques struggle to end this inexplicable curse, they begin to uncover the bloody history of their apartment.