In the Paris of 1835, Vicomte de Prony (Michael Lonsdale) visits his young friend Vellini (Asia Argento), a flamboyant Spanish woman in her mid-30s to warn her that her lover of 10 years, the handsome but penniless Ryno de Marigny (Fu'ad Ait Aatou) is about to marry the aristocratic Hermangarde (Roxane Mesquida). Vellini brushes the threat aside, confident in her bond with her Ryno. A few days before the wedding, Hermangarde's grandmother, Marquise de Flers (Claude Sarraute) confronts the young libertine with his past, and especially his attachment to Vellini, and asks why she should trust him to make her granddaughter happy. Ryno de Marigny convinces her he means to remain loyal and reveals details of his past, including the trauma that changed his relationship with Vellini. She consents to the marriage - but the old mistress isn't content to be forgotten.