Without regard for the consequences, the Duke of Mantua seeks erotic distractions from his boredom. He is currently after Countess Ceprano, whose husband is mocked by the hunchbacked court jester Rigoletto. Meanwhile, courtier Marullo announces, the latest gossip is that Rigoletto keeps a mistress at his home. When the jester suggests to the Duke that he should imprison and behead his troublesome rival, Ceprano and the other courtiers vow an overdue retribution.
Suddenly Count Monterone appears, demanding to speak to the Duke. He furiously claims redress for the seduction of his daughter. When Rigoletto, as before with Count Ceprano, makes fun of him, Monterone lays a curse on the Duke and his jester for mocking a father’s tribulation.
On his way home Rigoletto comes across Sparafucile, a hired assassin who discreetly offers his services, should he for instance want to get rid of a rival. Rigoletto sends him away, but reflects that he and the murderer are two of a feather: he kills with his tongue, the other with his dagger.
It is Gilda, his daughter, whom Rigoletto keeps shut up at home under the surveillance of Giovanna. Rigoletto looks in to see if all is well; Gilda wants to know about her parents, but Rigoletto names her neither her father nor her dead mother. Once more he tells her not to leave the house, if only to go to church, but here again he is not willing to tell Gilda why not.
Hearing noises outside, Rigoletto goes out to investigate. For a moment Giovanna lets the girl out of her room, and Gilda tells dreamily of a man who had caught her eye at church. A voice chimes into hers and she recognizes the strange man, who is the Duke masquerading as a poor student, and who declares his love for her. As Rigoletto can come back at any moment, they part soon, leaving Gilda to sing of her new love.
Night has meanwhile fallen, and Ceprano arrives with a group of courtiers, determined to teach the cynical jester a lesson by abducting the girl they take to be his mistress. When Rigoletto comes back, he meets the gang, who tell him they are there to abduct Countess Ceprano for the Duke. Believing that Gilda is safe and not recognizing the kidnappers in the bad light, Rigoletto joins in the fun and helps them. Too late he realizes that he has been duped, and he recalls Monterone’s curse.
The Duke regrets the disappearance of Gilda, but the triumphant courtiers restore his spirits by telling him that they are bringing him Rigoletto’s mistress, whom they have abducted.
Rigoletto enters, doing his best to conceal from the courtiers his anxiety for his daughter. He soon deduces that Gilda must be in there with the Duke, but pleads in vain to be allowed to see her, finally confessing that he is her father.
Gilda rushes out of the Duke’s room into his arms, and the courtiers now leave father and daughter together. Gilda tells her father of her love for the fake student and the shame it has brought upon her. Rigoletto swears vengeance.
To cure Gilda of her infatuation for the Duke, Rigoletto resolves to show her proof of her lover’s infidelity. Unwillingly she watches the disguised Duke making love to Sparafucile’s sister Maddalena just as he had courted her. But her love for him is still not dead.
Rigoletto orders Gilda to leave town. He will go with her, but first he intends to have Sparafucile murder the Duke. However, Gilda overhears this. As Maddalena persuades her brother to supply Rigoletto with some other victim, Gilda resolves to sacrifice her life for her lover. She knocks on the door and Sparafucile kills her. At midnight, as agreed, the murderer hands over to Rigoletto the sack with the corpse. Rigoletto rejoices, but then he hears the voice of the Duke; opening the sack, he discovers his dying daughter.