Pierre, a middle-aged tourist guide, collapses suddenly. He has no idea where he is. He returns home and finds Antoine, a mysterious young man whom he doesn't know, waiting for him to exact revenge a woman whom he apparently loved who has hung herself. What exactly is Pierre's degree of responsability in this matter ? In a night-club where they go together, Pierre meets Ninon who, according to Antoine, dances like the woman who committed suicide. Suddenly, he remembers an elegant and very beautiful woman whom he met when travelling about the country to sell the Encyclopaedia Briannica. He remembers that he desired her. This woman, during their conversation, made a confession to him : she was passionately in love with a young man aged 11, her husband's son...