The home of Donna Anna. Leporello complains about his work as a servant, while his master pursues an amorous adventure. Don Giovanni, masked, hurries out of the house, chased by Donna Anna, and then by the Commendatore, her father, who draws his sword to free his daughter from this unknown intruder. Don Giovanni deals the Commendatore a mortal blow. Donna Anna is overcome with grief. She returns with her fiancé Don Ottavio, who tries to comfort her, and they swear to avenge her father.

In the morning Giovanni and Leporello overhear a woman’s lament. Giovanni approaches to seduce her, and then realizes she is Donna Elvira, whom he has already seduced and abandoned. He manages to escape her, leaving Leporello to explain that she is but one entry in a formidable catalogue of conquests.

Later they come upon a jovial working-class wedding. Giovanni flirts with Zerlina, the bride, and invites the entire party to his villa. The groom, Masetto, is duly disgruntled, but distracted by Leporello. Giovanni and Zerlina are left alone – until Elvira interrupts and sweeps Zerlina away. Anna and Ottavio enter, asking Giovanni’s help in finding the killer of Anna’s father. Elvira interrupts again, denouncing Giovanni; but he claims she is mad. Suddenly Anna recognizes in Giovanni’s speech the voice of her father’s murderer and her attacker. Back in her boudoir, she describes the scene to Ottavio, and they both swear vengeance again.

At Giovanni’s home, Zerlina tries to calm a jealous Masetto. Giovanni leads them both back to the party. Three masked figures (Anna, Elvira, and Ottavio) make their entrance. The dancing begins. Giovanni leads Zerlina into an adjoining room and when her screams are heard, everyone rushes to her aid. Giovanni seizes Leporello and tries to blame him, but no one is deceived. Anna, Elvira, and Ottavio unmask and denounce Giovanni as the Commendatore’s assassin. Giovanni flees.

The foyer of Donna Elvira’s hotel. Giovanni and Leporello exchange clothes so that Giovanni can woo her pretty housekeeper. Elvira falls for the trick, and Giovanni sings a melting serenade to the maid. Masetto arrives with a band of peasants on the hunt for Don Giovanni. Giovanni divides them up and sends them off, and gives Masetto a beating. Zerlina hears his groans and comes to console him.

Leporello, still disguised as Giovanni, is trying to shake Elvira when Anna, Ottavio, Zerlina, and Masetto surprise him and demand his death. Leporello reveals his identity, begs for mercy, and manages to escape. Ottavio swears vengeance. Elvira reflects on her betrayal and her enduring love.

Giovanni and Leporello hide in the funeral chapel. They hear a solemn voice and realize it is coming from the Commendatore, whom Giovanni orders Leporello to invite to supper. The Commendatore’s ghost nods his assent.

Ottavio hints at his forthcoming marriage to Anna, and she reproaches him for speaking of it so soon after her father’s death.

Giovanni seats himself for supper. Elvira enters, demanding that he mend his ways. He sends her away, and her shriek is heard in the corridor, only to be echoed by Leporello’s: the Commendatore has come to dine. He confronts Giovanni with his horrifically guilty conscience. Giovanni is tortured but declares he will not repent. The Commendatore exacts his revenge. The other characters deliver the moral of the story: the lives and deaths of evildoers are always the same.