Act I

The garden

Don Anchise, the mayor (podestà), is hopelessly attracted to his new gardener Sandrina, much to the consternation of the jealous housekeeper Serpetta. But Sandrina is not who she at first seems: she is in fact the Marchioness Violante in disguise. She has come to the mayor’s mansion and has disguised herself as gardener to search for her erstwhile fiancé, Count Belfiore, who had stabbed her in a fit of jealousy and left her for dead. Belfiore, however, has since become engaged to the mayor’s niece Arminda, who is in turn being courted (so far in vain) by her ex-flame Ramiro. Violante’s servant Roberto, himself disguised as Sandrina’s cousin Nardo, has in addition fallen for Serpetta, who teases him but has her sights set firmly on her boss.

Sandrina faints when she learns of the upcoming marriage between Arminda and Belfiore, who then recognizes her. Confusion ensues as everyone is consumed by jealousy.

Act II

Scene 1: In the hall of the mansion

Arminda confronts Belfiore about his reaction to seeing Sandrina and Ramiro produces an arrest warrant accusing Belfiore of murder. Before Belfiore can respond, Sandrina reveals that she is Violante to save him but then denies it again once alone again with Belfiore. Arminda, who has in this way had her suspicions confirmed of Belfiore’s previous romance, has Sandrina kidnapped.

Scene 2: In the forest

Abandoned in the woods, a terrified Sandrina takes shelter in a cave. Don Anchise, Belfiore, Serpetta and Nardo search for her. In the darkness, the mayor mistakes Arminda for Sandrina and she confuses him for Belfiore, while Belfiore thinks Serpetta is Sandrina and she thinks he is the mayor. When Ramiro appears with torches, the embarrassed and mismatched couples separate. Belfiore and Sandrina lose their senses and conclude they are the Greek gods Medusa and Alcides.

Act III

The courtyard of the mansion

When Sandrina and Belfiore awake, their senses restored, they reconcile. Nardo reveals that Sandrina is Violante, and Arminda then resigns herself to marrying Ramiro after all, as does Serpetta to Nardo. The mayor announced he will find a new gardener to marry.