NOTE: Don Pasquale is usually set in nineteenth century Rome, Italy. San Diego Opera's production is set in the American West at about the same time. While the libretto and music are unchanged, some of the action may be different from that of the traditional performance described below.
ACT I: A room in Don Pasquale's house.
The elderly, wealthy (and miserly) bachelor, Don Pasquale, wants his nephew, Ernesto, to marry a wealthy woman he has chosen for him, but Ernesto, who is in love with the beautiful but poor widow, Norina, has refused. Therefore, Don Pasquale has decide to marry himself, disinheriting his nephew, and has asked Dr. Malatesta to help him find a suitable bride. The doctor agrees, but as he is a friend to both Ernesto and Norina, he decides his 'help' will be a trick which will allow the young couple to marry. As the Don paces nervously up and down, Maletatesta arrives, announces he has found the perfect bride for him and proceeds to describe her (Bella siccome un angelo — Beautiful as an angel). She is his sister, Sofronia, who has been raised in a convent and is innocent of the world. The enraptured Pasquale demands to meet her at once and sends Malatesta to fetch her. Left alone he imagines his future happiness with his wife and half a dozen children (Un foco insolito — An unusual fire). These happy musings are interrupted by Ernesto. His uncle gives him one more chance to marry the wealthy woman he has chosen, but Ernesto is determined to marry Norina. Pasquale then unloads his bombshell; he is getting married himself and Ernesto must find a new place to live! Thinking at first that his uncle is joking, Ernesto finally realizes he is serious and urges him to seek the advice of Dr. Malatesta. He is dumbfounded to learn that, not only has his friend, Malatesta, encouraged the marriage, but has also provided his sister as the bride-to-be.
The scene changes to Norina's house.
As she reads a story of how a woman's glance captured a knight, Norina boasts that she too knows the magic of such a glance (So anch'io la virtù magica — I also know the magic power). Dr. Malatesta is trying to devise a scheme which will enable her to marry Ernesto, and she is waiting to hear from him. A letter is brought from Ernesto (who doesn't know what they are doing). Believing his uncle at last, he writes that they must give up their love. He is leaving Rome that very day. Malatesta arrives and explains his idea to Norina. She is to make-believe that she is his sister, a shy, simple girl (he really does have a sister Sofronia who is being raised in a convent). Don Pasquale will fall madly in love with her, and his cousin can perform a fake ceremony (Pronta son io — I am ready). They will then lead him such a merry dance that he will do anything, including allowing Ernesto to marry the bride of his choice, to get out of the nightmare marriage. He coaches her on how to behave, and they gleefully anticipate the results of their trick (Vado, corro — I am hurrying).
ACT II: Don Pasquale's house
Ernesto bemoans his fate and vows go far away. Although that will not erase Norina from his heart, he will be satisfied if she is happy (Cercherò lontana terra — I will seek a distant land). He leaves as Don Pasquale enters, followed by Dr. Malatesta and a heavily veiled "Sofronia". She pretends to be terrified but constantly utters asides which express her real thoughts about the old man. When her veil is removed, Pasquale is so overwhelmed by her beauty, gentleness and pliability, he demands an immediate wedding. The "notary" arrives and a marriage contract is drawn up in which the besotted Pasquale promises her half of everything he possesses. She will also be the absolute mistress of the house. They are about to sign when Ernesto appears. He still has not been told of the plan and is furious at the scene which greets his eyes. Norina and Malatesta manage to signal him to go along with the charade, and all sign the contract. Immediately the shy, docile Sofronia is gone, replaced by a shrew who prevents her new 'husband' from embracing her. She declares Pasquale is too old and too fat to take her out; Ernesto will be a more appropriate escort. She orders more servants (young, good-looking ones), a pair of carriages with horses, furniture, clothing, a dinner party for fifty, etc. Pasquale protests in vain, he is no longer the master of the house, merely a peasant bumpkin and a boor. Furiously, he realizes he has been played for a fool.
ACT III: Don Pasquale's house
Servants bustle about, and a despairing Pasquale peruses the bills. Norina is going to the theatre, and when he protests, she tells him to keep his mouth shut and go to bed. In response, he threatens divorce. As she leaves, she 'accidently' drops a letter which arranges an assignation for that evening.
A little later Ernesto and Malatesta discuss the rest of their plan. Ernesto will be the man Sofronia meets in the garden. After he leaves, Pasquale returns and tells Malatesta he is desperate to end the marriage, even if it means allowing Ernesto to marry his Norina. Once again, Malatesta is willing to 'help'. He and the Don will hide in the garden to observe the meeting. If Sofronia proves to be unfaithful, Pasquale will be able to throw her out.
In the garden, Ernesto sings of the evening, begging his love to come to him (Com'è gentil — How lovely). When Norina appears, they sing of their love (Tornami a dir — Tell me again). Pasquale and Malatesta try to confront the couple, but Ernesto has disappeared, and Norina swears he was never there. Once more Malatesta is called on to help and to persuade his 'sister' to leave. The doctor says some things to her loudly enought for Don Pasquale to hear (she had better leave; tomorrow a new wife will come to the house, Ernesto's wife Norina) and other things, sotto voce, for her alone (telling her to pretend to fly into a rage). She agrees to go provided it is really true that Don Pasquale will allow the marriage of the young people. When Ernesto arrives, Don Pasquale tells him he is now in favor of the marriage, and he should fetch his Norina. But the bride is already there; Sofronia is Norina! Malatesta's real sister is still at the convent. They all ask his pardon for the trick they have played, and Don Pasquale ruefully says he got what he deserved. They all agree that an old man who marries is looking for trouble (La morale in tutto questo — The moral of all this).