Eleven years after the presentation in the parallel section of Perfect Love, French director Catherine Breillat is competing for the Palme d'Or for the first time with Une Vieille Maîtresse. Adapted from the novel of the same name by Jules Barbey d'Aurevilly, the action in this feature takes place in the mid-19th century. Licentious young Ryno de Marigny (Fu’ad Aït Aattou) is engaged to the virginal Hermangarde (Roxane Mesquida), the fine flower of the aristocracy. But ill-wishers determined to prevent the match, despite the love of Ryno and Hermangarde for each other, spread rumors that the young man will never succeed in separating from La Vellini (Asia Argento), the mistress who, for years, has been his scandalous flame.

Asked whether Une Vieille Maîtresse is likely to appeal to the general public, Catherine Breillat replied: "This is my most accessible film for the general public, and yet I did not betray myself. It is completely unlike the films I usually make in that it  does not break any taboos. I had taken that style as far as it would stretch; it was time to come back to the essentials in life: pleasure, romance, and passion. But romance is dark, which was another reason for wanting to make this film; for the romanticism, the burning passion, the terrible suffering, but without perverting the sentiments. The heart of the story portrays an ideal that topples into disaster as soon as it is reached."