When mother of two children Myriam decides to go back to work despite her husband's initial reluctancy, the couple starts looking for a nanny. After a very selective process, they finally find the perfect candidate, Louise, a poised 40-year old woman who is an instant hit with both kids and parents. But as Louise makes herself indispensable to the family, she starts revealing her true self and her behavior becomes more and more unsettling to those around her.