In this first film in Eric Rohmer's cycle of "Comédies et proverbes," François (Philippe Marlaud), a young student working nights as a postman, is in love with a slightly older woman, Anne (Marie Rivière). One day, he sees Anne's former lover, a pilot named Christian (Mathieu Carrière), leaving Anne's apartment in the morning. Despite Anne's explanation that Christian is now married to another woman and simply dropped by to talk, François becomes jealous. He starts spying on Christian in order to find out if his rival secretly sees Anne. Though François sees Christian meeting a different woman, he keeps following the pair. His pursuit leads him to a park where he meets up with a vivacious teenage girl named Lucie (Anne-Laure Meury), who becomes curious about his motives and agrees to help him in his detection.