Gianni (Teddy Reno), their sister Lucia (Vittoria Crispo)'s son, is studying medicine in Naples, when he falls in love with Marisa (Dorian Gray), a revue dancer, and follows her to Milan.

The news is broken to the family with an anonymous letter, and the three brothers travel to Milan in an attempt to stop the relationship, which they consider dangerous.

Antonio and Peppino try to bribe Marisa away from Gianni but he woos her back by moving her to tears with the song "Malafemmina", and Lucia realizes that she is a good girl.

Memorable in the history of comedy films is the scene in the movie where Toto and Peppino (the Capone brothers) have to write a simple letter to be sent to their nephew.

Yet Toto, who is believed to be the bright one, dictates a letter to his brother that is so full of grammatical and syntactical errors to make it unintelligible.