Leporello is furious: Once again, he must keep watch while his master is having his way with a woman.
Don Giovanni is pursued by Donna Anna, determined not to let the nocturnal intruder get away. When her father challenges the seducer to a duel, he is killed by Giovanni.
Donna Anna demands that her fiancé Don Ottavio seek bloody revenge for this murder.
Don Giovanni tries his luck with the next best woman, but it turns out to be ill luck: It is Donna Elvira, whom he has already seduced and deserted. He steals away, and Leporello describes his master to Elvira as a large-scale consumer of female charms and shows her the extensive catalogue of seduction victims.
Don Giovanni is working on his next conquest: He steals peasant Masetto's bride from him on the very eve of the wedding, and invites the entire wedding party to his palace. Masetto rages is in vain, his Zerlina is not at all unwilling, especially since the noble gentleman promises marriage. But Donna Elvira intervenes and snatches Zerlina from Giovanni's claws.
Don Giovanni meets Donna Anna and her intended. She asks his help in looking for the murderer. Just then Donna Elvira returns and accuses Giovanni of having betrayed her. He tries in vain to present her as insane, and has to beat a retreat with her in tow.
He has only just left when Donna Anna claims that she has recognized Don Giovanni's voice – he is her father's murderer. She reminds her fiancé of his oath of revenge. But Ottavio would rather file a proper lawsuit against Giovanni.
Don Giovanni makes Leporello report on the preparations for the marriage feast. He wants to make use of the night for new conquests.
Zerlina has only just succeeded in pacifying Masetto when Don Giovanni approaches. Masetto becomes suspicious once more and eavesdrops on the pair. Giovanni discovers him but passes lightly over the embarrassing situation. All three hurl themselves into the bustle of the festivities. Donna Anna, Donna Elvira and Don Ottavio mix with the party guests to spy on Giovanni.
The orgy is taking its course, when suddenly Zerlina screams for help. Giovanni puts the blame on his servant and threatens to kill him. The three noblemen and the peasant couple are not fooled by this, however, and call for Don Giovanni's death. The feast ends in general confusion.
Leporello thinks his life is becoming too dangerous, he wants to quit his master's service. Don Giovanni soothes his anger with money.
Now he wants to seduce Donna Elvira's maid and switches clothes with Leporello. Donna Elvira is lured from the house with renewed vows of love; Leporello in disguise must play Don Giovanni to her.
The way to the maid has only just been cleared when Masetto and the other peasants arrive to look for Giovanni and kill him. Mistaken for Leporello, Don Giovanni succeeds in sending them off on a false scent. Then he settles his account with Masetto.
Leporello is trying to throw off Donna Elvira, when he is confronted by Donna Anna, Don Ottavio, Masetto and Zerlina. They take him for his master and want to kill him. Donna Elvira pleads for the man she takes to be her lover. Leporello reveals himself and makes use of the ensuing confusion to take his flight. Don Ottavio, now finally convinced of Giovanni's guilt, decides to turn to the authorities. He desperately clings to the hope that everything will be better after Don Giovanni has been removed.
Leporello meets up with his master again. In a fit of high spirits, Giovanni commands his servant to invite the statue of the dead Commendatore to dinner. Trembling with fear, Leporello acts out the order, and is deeply appalled when the dead man accepts.
Donna Anna and Donna Elvira try to assist each other in dealing with their pain.
Don Giovanni wants to conclude his day of failures with a pleasant dinner. Donna Elvira comes to ask him to change his life. Don Giovanni mocks her until she leaves, her mission uncompleted. At the door, she screams out in fear. Don Giovanni and Leporello cannot imagine why – Leporello is sent off to enquire. But the news that the statue of the dead Commendatore has indeed arrived does not move Don Giovanni to repent and change. He challenges fate, realising too late that his last hour has come.