(uncredited)
En 1485, el Demonio envía al mundo a dos emisarios, Dominique y Gilles, que se presentan en el castillo del Barón de Hughes, que está celebrando el compromiso de su hija con el caballero Renaud. Como Gilles, en contra de los planes de su Señor, se enamora de la joven, el Diablo acaba presentándose en el castillo adoptando la figura de un viajero.
Gilbert, poet and singer, is about to marry Lilette but deep inside himself he is not quite sure that she is the woman he needs. That is the reason why he has made up an imaginary woman, Frédérica" to whom he writes love letters, actual ones this time. When Lilette finds one of these, she sees red. Théodule, one of Gilbert's many friends, sets out the problem with the help of Claudine, his own girlfriend, posing as Frédérica. After Gilbert and "Frédérica" have played a phony breakup scene in front of Lilette, things seem to come right when... another Frédérica appears...
As her neighbor Rémi Courmont has told her off for making his ears bleed with Ravel's Bolero, a music piece she plays at full volume all the time, Anne-Marie decides to get even with him. She sets up a hoax with the complicity of her friend Catherine, who agrees to post as Remi's mistress to embarrass him. Just then, Niquette, Rémi's real lover, resurfaces.
