Leporello is standing watch outside the house of the Commendatore while his master, Don Giovanni, is inside on his usual business of attempting to seduce a woman. Leporello grumbles about the hours (Nolte e giorno faticar) and says he wants to quit and live like a gentleman. He moves out of sight when Donna Anna, the Commendatore’s daughter, appears hotly pursuing the masked Don Giovanni, who has been trying to seduce her by force. Her cries for help soon attract the Commendatore to challenge the arrogant Don Giovanni, who does not want to fight the old man, but, when forced to do so, quickly dispatches him. Don Giovanni and Leporello leave just as Donna Anna returns with her fiance, Don Ottavio, in search of the attacker. Seeing her father’s body, Donna Anna calls for vengeance, which Ottavio promises.
Leporello catches up with his master and tries to quit his job, giving as reason the Don’s scandalous behavior, but is quickly cowed into submission. Just then a woman passes nearby, and the Don slips into the shadows to observe her. Donna Elvira, a lady from Burgos, enters the square, looking for the faithless lover who abandoned her (Ah! chi mi dice mai). Though Giovanni himself is the faithless lover, he does not recognize her and thinks he should offer consolation. As soon as he steps forward, they recognize each other. As he tries to retreat, she heaps recriminations on him for having seduced her with promises of marriage, only to leave after three days. Saying Leporello will explain, the Don Giovanni ducks out, leaving Leporello to break the news that Elvira is but one of a legion of women so deceived. From his catalogue he reads off all the kinds of women and the various places where his master enjoyed success with them—an amazing total of 1170 to date– (Madamina!) as Elvira vows her revenge,
In the countryside two young peasants, Zerlina and Masetto, are celebrating their betrothal with a group of friends. Giovanni and Leporello happen upon the scene and Zerlina immediately catches the nobleman’s eye. He invites the party to his castle to continue their celebration, quietly telling Leporello to distract Masetto. However, as Leporello tries to lead him off, the young man defiantly declares that this “noble lord” is up to no good (Ho capito). Now alone with the girl, Don Giovanni tells her she shouldn’t marry such a bumpkin, but should come instead to his castle, where he will make her his wife (La ci darem). Their idyll is punctured by the arrival of Elvira, who rants at the would-be seducer and urges Zerlina to escape (Ahi fuggi) as she leads her away. No sooner have the two women left than Anna and Ottavio appear. Just as Anna asks Giovanni’s help in finding her unknown assailant, Elvira returns and advises Anna against trusting such a traitor (Non ti fidar). Anna and Ottavio are impressed by the strange woman’s nobility and sincerity, as Giovanni tries to explain that she is out of her mind. Finally, Giovanni insists that he himself will escort Elvira away and kisses Anna’s hand as he departs. As soon as he is out of sight, Anna suddenly declares that she recognizes Giovanni as her father’s murderer. She recapitulates the events of the evening before, describing the tone and bearing of the would-be seducer, then tells Ottavio to avenge her (Or sai chi l’onore). She withdraws, leaving Ottavio to declare he will not rest until he has satisfied her call for justice (Dalla sua pace).
At Giovanni’s castle, Leporello tells him what happened when the peasants arrived at the castle: they started drinking and partying, but Donna Elvira burst in with Zerlina. Only after she had delivered a tirade against Don Giovanni was Leporello able to push her out the back door and lock it. Disregarding Leporello’s complaints, Don Giovanni toasts his plans to enjoy the coming evening and augment his list of conquests. (Finch’han dal vino).
Outside, Zerlina tries to conciliate the angry Masetto with a mixture of innocence and penitence (Batti, batti, o bel Masetto). But when Don Giovanni’s voice is heard in the distance calling everyone to celebrate, Masetto’s suspicions flare up again. Zerlina and Masetto try to hide, but Giovanni finds her—and, stepping out of the shadows, Masetto reminds him that he is there, too, and they return to the castle. Three masked figures appear—Elvira, Anna, and Ottavio. Seeing them from a window, Leporello calls Don Giovanni, who tells him to invite them in.
In the ballroom, with the party under way, Masetto warns Zerlina about the Giovanni’s advances. Leporello welcomes the trio of maskers and the host toasts them, including everyone’s freedom to enjoy himself as he wishes (Viva la liberta!). When the dances begin, Leporello distracts Masetto by forcing him to learn to dance as Don Giovanni drags Zerlina into a nearby bedroom. Abruptly, an offstage cry from Zerlina interrupts the party and the maskers move to protect her as she runs back into their midst. She is followed by Giovanni, who claims it was Leporello who assaulted her. When the three maskers reveal their identities, Giovanni recognizes the plot has turned against him and defiantly dashes out.
Outside the lodging of Donna Elvira, Leporello angrily decries his most recent endangerment at the Don’s hands. Giovanni mollifies him with money and describes their next escapade. He will court Elvira’s maid after Leporello, disguised in Giovanni’s hat and cloak, lures Elvira away from the scene. Spotting Elvira at her window, the Don pretends to be repentant, but she declares she will not trust him. However, she quickly changes her mind and comes down to the courtyard, to be welcomed by Leporello, whom she takes for the Don. Giovanni puts on Leporello’s hat and cape and serenades the maid (Deh vieni), but when she appears at the window, Masetto enters leading some armed peasants in search of the culprit. Distinguished as Leporello, Giovanni tells them to divide into two groups and whoever finds the pair of strolling lovers should attack (Meta di voi qua vadano). He coaxes Masetto stay behind to share a “secret,” which turns out to be a harsh thrashing using the young man’s own weapons. As Giovanni escapes, Zerlina enters to find her beaten and bruised sweetheart and, after scolding him for doubting her fidelity, promises to nurse him back to health (Vedrai, carino).
Back in the courtyard of Elvira’s lodging, Leporello enjoys his fake courtship but plans to slip away on the pretext of meeting her later. While she bemoans her state of perpetual abandonment (Sola in buio loco), he hides in a doorway. Anna and Ottavio approach, now joined by Zerlina and Masetto, all bent on vengeance. When they discover Leporello, Elvira alone begs for mercy for the supposed Don Giovanni, saying she is his wife. Leporello finally reveals his identity and begs them not to beat him (Ah, pieta! Signori miei). Taking advantage of their angry distraction, he escapes. Ottavio asks the others to comfort Anna while he searches for the real culprit to avenge his beloved (II mio tesoro). Elvira laments that her tormented heart still feels pity for the man who betrayed her (Mi tradi).
Fleeing from the others, Don Giovanni and Leporello meet in the cemetery. As they compare notes on their respective narrow escapes, a somber voice from behind announces that Giovanni’s laughter will end before morning. Suspecting a joke, they discover the Commendatore’s statue on his grave. Don playfully forces Leporello to invite the Statue to dinner that same night, and, amazingly, it nods in acceptance.
Ottavio reassures Anna in her house that Don Giovanni will pay for his crimes, but she delays their marriage plans by saying that mourning for her father has preempted her devotion (Non mi dir).
Preparing to enjoy dinner in his castle, Giovanni orders his musicians to play and they offer selections from three popular operas of the day. When they reach the third, Le nozze di Figaro, Leporello remarks that it has been heard too often. As the men start eating, Elvira rushes in, pleading with Giovanni to save himself by repenting at once. Seeing from his jovial and indifferent attitude that her mission is doomed, she leaves, but screams in fright from the anteroom. Leporello, saying he hears the statue’s approaching steps, refuses to open the door and hides under the table. Giovanni, however, admits the stone guest, who refuses earthly food but invites the Don to dine at his own table–after demanding that he repent or face damnation. Unafraid, the Don offers his hand, which the statue grips. When Don Giovanni refuses to repent, the statue disappears and Giovanni falls to the floor, gasping, as unseen spirits announce his consignment to hell. Amid rising smoke and flames, he sinks out of sight.
Anna, Ottavio, Elvira, Zerlina, and Masetto burst into the room searching for Don Giovanni but Leporello tells them the most recent turn of events. Anna asks Octavia to wait a year before marriage; Elvira will retire to a convent; Zerlina and Maseto head home for dinner; and Leporello looks forward to finding a better master at the tavern. They close with a refrain, “Such is an evildoer’s end: death is the just reward for a misspent life.”