Diane (Brigitte Rouan) is a forty-something, chic and sophisticated book editor. Her home life is also content; she is married to a lawyer, Phillipe (Patrick Chesnais), whom she still loves despite their passion having waned, and is devoted to her two teenage boys. Professionally, Diane’s preoccupation is guiding talented but self-doubting author Francois (Nis Tavernier) through his second novel. But when she meets Francois’ flatmate, Emilio (Boris Terral), she tumbles into a frenetic affair that soon becomes, for her, a deep obsession. Coincidentally, Diane’s husband, Phillipe, is defending an elderly neighbour who has murdered her own husband after being tormented by his infidelities over many years.