Despite the reluctance of her husband Paul Myriam, the mother of two young children, decides to resume her activity in a law firm. The couple starts looking for a nanny. After a thorough interview process, they hire Louise, who quickly conquers the children's affections, and gradually occupies a central place in the family's home. But very quickly Louise's reactions became worrying. Everyone will gradually get caught in the trap of mutual dependence, until tragedy strikes.