Luca Cupiello, like every Christmas, prepares the crib, amid the disinterest of his wife Concetta and his son Tommasino. Ninuccia, the other daughter, writes a letter to her husband in which she communicates that she leaves him for her lover. The letter happens in the hands of Luca who hands it over to his son-in-law, who thus learns of his wife's betrayal. During lunch on Christmas Eve, the two rivals, who were confronted by Luca's carelessness, clash violently.