The wealthy bachelor Don Pasquale is furious that his nephew Ernesto has fallen in love with a penniless widow. Pasquale decides to get married himself so he can disinherit his disobedient nephew and produce a new heir. Pasquale consults Dr. Malatesta, who suggests his own sister as a bride. Elated, Pasquale instructs Malatesta to arrange the meeting. Ernesto arrives and once again defies his uncle’s orders to choose a more suitable bride. Pasquale shares his own marriage plans and kicks Ernesto out of the house. The young man is devastated by the loss of his inheritance and his future with Norina.  

Malatesta visits Norina and lays out his plan: she will pretend to be his sister, marry Pasquale in a mock ceremony, and then make him so miserable that he would do anything to be rid of her. Norina accepts. 

Oblivious to the plan, Ernesto mourns the loss of Norina and his impending exile. Meanwhile, Pasquale can’t wait to meet his new bride. Malatesta arrives and introduces Pasquale to his timid sister “Sofronia.” Pasquale is smitten and decides to hold the wedding immediately. Just as the ceremony begins, Ernesto bursts in, accusing Norina of betrayal. Malatesta discreetly explains the plan to Ernesto, who then agrees to witness the marriage. Once the contract is signed and Pasquale hands over his fortune, Norina sheds her demure façade and declares herself the master of the household. Pasquale is left stunned. 

As Norina indulges in lavish spending, Pasquale is infuriated at his growing mountain of bills. Norina mocks Pasquale, but in her heart of hearts, she begins to feel some sympathy for the old man. As she leaves for the theater, she drops a letter for Pasquale to find, suggesting a secret rendezvous with a lover. Alarmed, Pasquale calls for Malatesta, who assures Pasquale that they will catch “Sofronia” in a compromising situation. 

Norina is serenaded by Ernesto, and they profess their love for each other. Pasquale and Malatesta arrive too late to catch Ernesto, who slips away as Norina plays the dutiful wife. Malatesta then announces that Ernesto plans to introduce his bride to Pasquale, who has no idea that Norina is, in fact, the widow that Ernesto loves. “Sofronia” acts enraged at the idea of sharing her home with another woman, leading Pasquale to joyfully permit Ernesto to marry Norina and restore his inheritance. When the truth about “Sofronia” is revealed, Pasquale accepts the outcome with good humor and gives the couple his blessing.