The Burghezia in the Landes department is proud to announce in 1928 the marriage between Thérèse and Bernard Desqueyroux, whose union will allow the creation of a single pine forests. Disgusted by her husband, overwhelmed by the possession of her mother-in-law, Madame de la Trave, Thérèse, pregnant, does everything in her power to escape this marriage. Thérèse gives birth to a little girl. A dosage error committed by her husband manipulating her arsenic drug gives Thérèse the saving idea. If she missed the dose every day? Could he get rid of his husband?