Near the home of the Commendatore, Leporello bemoans his lot in life as servant to Don Giovanni. His thoughts are interrupted by screams from Donna Anna, who calls for help as a disguised Giovanni tries to flee. Her father, the Commendatore, attempts to defend her honor in a duel, but is killed by the lecherous Don, who then escapes. Don Ottavio also comes to Anna’s aid and promises to avenge her father’s death.
Elsewhere, Giovanni spots a new possibility in the distance, but to his horror, it is Donna Elvira, a woman he left behind in Burgos. As Leporello distracts her, Giovanni again slips away. His servant bares the bitter truth – she’s hardly the first to be betrayed as he rattles off the list of conquered women, one thousand and three in just Spain alone.
In the countryside, Zerlina celebrates her upcoming marriage to Masetto with a group of peasants. Giovanni and Leporello soon appear and the former is entranced by the country girl. To distract her fiancé and the others, he offers to celebrate the nuptials with food and drink at his mansion nearby. Zerlina remains behind as Masetto is assured that his bride-to-be will be safe in the hands of a gentleman. Giovanni quickly puts on the charms with a promise of marriage, which Zerlina momentarily considers. They are interrupted by Elvira, who warns the young woman to beware of his treacherous words.
No sooner has Elvira spirited Zerlina away does Giovanni happen upon Anna and Ottavio. They enlist his assistance in finding the murderer of her father. Again, Elvira intercedes, professing Giovanni’s true nature. He discounts her statements as madness and follows her, feigning concern over her mental state. Anna suddenly realizes that Giovanni is her would-be rapist and her father’s killer. She cries for vengeance.
At Giovanni’s palace the party is in full swing. Masetto questions Zerlina’s fidelity, and when she tries to reassure him, it is to little avail. Elvira has joined Anna and Ottavio, and the three of them arrive at the party masked. As everyone begins to dance, Giovanni leads Zerlina into another room. Her screams are soon heard, and as Giovanni tries to deflect the blame on Leporello, he is able to escape once again.
On a street near the residence of Donna Elvira, Leporello threatens to quit, but is appeased by an influx of cash. Tired of this type of life, he begs Giovanni to put an end to his wanton pursuit of women, but the Don counters that to be faithful to one would mean to deny the others. His latest quest is the young and attractive maid of Donna Elvira. He exchanges cloaks with his servant to disguise his station. Leporello is to distract Elvira by posing as his employer.
Elvira is easily fooled, quite willing to forget past transgressions, and the disguised Leporello manages to lead her away. Meanwhile, Giovanni sings a serenade to lure the maid, but to no avail. Masetto enters with a posse of peasants, intent on capturing the scurrilous Don. Still dressed as Leporello, Giovanni manages to divert the other men, and alone with Masetto, gives him a sound thrashing. Zerlina enters and soothes the wounded man.
Meanwhile, Leporello is trying to lose Elvira in the darkness. Instead they encounter Anna and Ottavio and soon after, Zerlina and Masetto. All first recognize him as Giovanni, and are hardly any more forgiving once Leporello’s true identity is revealed. He begs for mercy, then runs off.
Near a graveyard, Giovanni and Leporello are reunited. The master brings his servant up to date – during their masquerade he was able to seduce none other than Leporello’s mistress. A voice interrupts his merriment, and the two find themselves in front of the Commendatore’s tomb. Responding to the inscription, which states that even in death the old man will have revenge on the traitor who put him there, Giovanni callously invites him to dinner. He accepts.
Elsewhere, Ottavio tries to ease Anna’s grief with an offer of marriage, but though she loves him, she will not be consoled. Back at the palace, Giovanni enjoys his dinner while Leporello picks at a few scraps. Elvira enters and makes one last attempt at getting the Don to change his dissolute ways, but he will not be persuaded. On her way out she is frightened by the ghost of the Commendatore, who also strongly advises Giovanni to repent.