In the garden of his mansion where both Sandrina (the noble Violante in disguise) and Nardo are hard at work, the Podestà appears followed by Cavalier Ramiro and Serpetta. They express their delight in the nice day, but only in jest so as not to show their true feelings of sadness. Sandrina is the former lover of Belfiore, who previously stabbed her and left her for dead, and now, in fact, lives in the same village. The Podestà is in love with his gardener, Sandrina, but she does not share his affections. Serpetta is in love with Nardo, but despite teasing and flirting with him, she does not return his gestures of love. Ramiro has just come out of a relationship with Arminda, who tossed him aside. Serpetta is angry at Sandrina for choosing not to love the Podestà. Finally, when he is finally alone with Sandrina, the Podestà confesses his love to Sandrina. She kindly lets him down, telling him she does not love him.
As a result of an arranged marriage, Arminda’s fiancé, Count Belfiore, arrives at the Podestà’s estate. When he meets Arminda for the first time, he is taken aback by her beauty. She immediately lets him know that she is a force with which to be reckoned, but Belfiore happily accepts her proclamation as a challenge.
While conversing in the gardens, Arminda mentions her engagement to Belfiore (Sandrina's former lover) in passing to Sandrina. Sandrina cannot believe it, and faints upon hearing the news. Arminda scrambles to her aid and leaves Belfiore in charge when he enters the gardens so that she can search for help. When Arminda comes back to the garden, she runs into Ramiro and neither of them are sure of what to say to one another. Sandrina awakens, only to find herself looking into the eyes of her former lover, Belfiore. The Podestà enters the garden and is confused by what he sees. After demanding an explanation, no one can seem to sort out their thoughts. Sandrina is hesitant to reveal her true identity, and Arminda suspects that she is being deceived. The Podestà concludes that Serpetta must be the cause of the confusion, but he is quick to point the blame to Sandrina. Meanwhile, Ramiro is the only one certain of his own situation, and that is the fact that Arminda does not have any feelings for him remaining in her heart.
Lost in thought, Belfiore mumbles to himself that he cannot find peace now that he has found his lost love, Violante. Soon thereafter, Sandrina walks into the garden. Nearly blowing her cover, she shouts at him for deserting her in the past. Belfiore is relieved that she really is his lost love. Sandrina quickly regains composure and tells him that she is not Violante, but rather her friend. She explains she was only stating Violante’s dying words. Despite the facts she is feeding him, Belfiore is enraptured by her - to him she shares the face of his former love.
Ramiro finds Arminda in the garden and scolds her. As they argue, Ramiro shouts that he will enact his revenge on Count Belfiore, but is interrupted by the Podestà. Arminda begs her uncle for permission to marry Belfiore, while Ramiro asks him to order Arminda to marry him. The Podestà is tired of all the drama and tells him to do what they want as long as they leave him alone. Arminda rejects Ramiro again and leaves the garden. Dejected, Ramiro gives up and concedes to the fact that he’ll never be able to love another woman and swears that he’ll die alone in misery.
Elsewhere in the garden, Belfiore confronts Sandrina one last time, and she finally admits to him that she is truly Violante. However, she tells him that she no longer loves him. Sad, but content to have her answer, he can finally leave without any doubts. After separating for just a few short minutes, neither of them can be apart after all, and they end up in each other's arms again. Arminda gives in to Ramiro and agrees to marry him, while Serpetta accepts Nardo’s advances. The Podestà accepts his fate of being alone for the time being, but remains hopeful that another Sandrina will cross his path.