Diane Cazerais (Brigitte Roüan) is a successful 40-something book editor in Paris, happily married to Philippe (Patrick Chesnais), a devoted attorney, with two teenage sons. Her structured, prosperous life unravels when she meets Emilio (Boris Terral), an attractive young engineer who is a friend of her colleague François. Overwhelmed by sudden, obsessive passion, Diane throws herself into an intense, secret affair with Emilio. However, as Emilio gradually grows distant and eventually abandons her, Diane succumbs to a severe emotional breakdown, desperately trying to conceal her psychological ruin from her oblivious husband and family.