Paul, a friendly Parisian cab driver, has two loves: music and his fiancée Virginie. After graduating from the Conservatoire with a first prize, he lives on hope, offering his classical works to publishers. One day, while driving customers to the races, he plays a "toquard": Maubeuge, who wins. With his friends, he celebrates the event and, for dessert, composes a song for the occasion: "Tout ça ne vaut pas un clair de lune à Maubeuge". Monique, a secretary at the radio station and one of the guests, had a record made of the tape recording. And this record, following a mistake, was broadcast on a religious music program. It's a runaway success: for Paul, it's fame and fortune. which he had obviously coveted, but more with his symphonies, opera and sonatas. No matter, the "Clair de lune à Maubeuge" (Moonlight in Maubeuge) allows two happily engaged couples to become happily married.