Cassandro, something of a pedant, bullies his brother Polidoro and objects to his sister Giacinta marrying Fracasso, and now Rosina, Fracasso's sister, is coming to stay in the house, seeking a husband and advised by Ninetta to set her cap at the first of the two brothers that she meets. This turns out to be Polidoro, who proposes at once, to his brother's later annoyance. Cassandro now starts to make overtures to Rosina. After a variety of incidents, including the departure of Giacinta with the family fortune, leaving the brothers unable to marry, all ends well enough. Rosina, teasing until the last minute, chooses, surprisingly, to marry Cassandro, Fracasso marries Giacinta and Simone finds again Ninetta, who also had absconded with whatever she could lay her hands on.

Mozart's opera was written for performance in Vienna, but this was prevented through what his father described as jealousy. The libretto presents a series of stock characters, in the tradition to which Goldoni was accustomed and the twelve-year-old composer dealt with this in comparable fashion, producing remarkable music and taking childish delight, in particular, in a duel scene between the braggart soldier Fracasso and the cowardly bully Cassandro, any serious outcome prevented by Rosina's timely intervention.