Jules, a young Parisian postman, secretly records a concert performance given by the opera singer Cynthia Hawkins, whom he idolises. The following day, Jules runs into a woman who is being pursued by armed thugs. Before she is killed, the woman slips an audio cassette into his mail bag...
Claude Massoulier is murdered while hunting at the same place as Julien Vercel, an estate agent who knew him and whose fingerprints are found on Massoulier's car. As the police discover that Marie-Christine Vercel, Julien's wife, was Massoulier's mistress, Julien is the prime suspect. But his secretary, Barbara Becker, while not quite convinced he is innocent, defends him and leads her private investigations.
Victor Valance, an absent father and gambler, works with shady casino operations abroad. When he returns to Paris in need of money, he plans to take advantage that Pauline, his eldest daughter now fully responsible for the whole family, has begun to work for the Ministry of Finance. Pauline thwarts his new projects but when she realizes gangsters are looking for Victor she will put her life at risk to help him and save their family.
