At a lavish party he is hosting, an amoral Duke reveals to his courtier Borsa that he has met a sweet young girl in church. She believes him to be an impoverished student, and he means to have her—and any other woman that catches his fancy. He particularly enjoys seducing women in front of their loved ones, as he proceeds to do with Countess Ceprano, knowing that her husband, the seething Count, can do nothing to avenge the dishonour. This insult is compounded by the Duke’s court jester Rigoletto, who mocks the Duke’s victims mercilessly and with absolute impunity, knowing that his boss will protect him from retaliation. The courtier Marullo hurries in with a delicious piece of gossip: Rigoletto has a mistress. The courtiers determine to strike back at the despised court jester. The evening’s festivities are brought to an abrupt stop by the arrival of Count Monterone, the outraged father of a young woman the Duke has debauched and discarded. Rigoletto viciously ridicules Monterone’s grief: in response, the Count hurls a vehement father’s curse at both the Duke (who is unaffected) and the jester (who is profoundly unnerved). Walking home through the dark back streets, Rigoletto is approached by Sparafucile—a self-described “assassin for hire.” The jester declines the assassin’s services—for now. Rigoletto arrives home to visit briefly with his beloved daughter Gilda, whom he has kept sequestered from the world in a convent since the death of her mother until recently bringing her to live with him—thus preserving her innocence, but also making her vulnerable to an outside world she does not really comprehend. In fact, she is the young girl the Duke has met at church, and whom he is wooing under an assumed name—Gaultier Maldé—and an assumed identity—a poor student. The ruse has been successful: Gilda has fallen in love from afar with this apparently ardent and idealistic young man. Of course she dare not tell her father; the young girl’s only guardian during Rigoletto’s frequent absences is her unscrupulous nurse Giovanna, who does not hesitate to accept a bribe from the disguised Duke, who arrives and professes love to the enraptured Gilda. Warned by Giovanna that someone is coming to the house, the Duke leaves, and the courtiers arrive to abduct Rigoletto’s “mistress.” They are interrupted by the jester’s return; he is easily fooled into helping them kidnap “Countess Ceprano,” but the real prey is his own daughter; by the time he comprehends that a trick has been played on him, Gilda has been abducted and taken beyond his protection. The father’s curse!

The next morning, the Duke is pouting because Gilda has apparently abandoned him. The courtiers arrive with their gift: Rigoletto’s “mistress.” Meanwhile Rigoletto, searching for Gilda, confronts the courtiers, revealing that the girl is not his mistress but his daughter, and begging for their compassion. The courtiers remain unmoved—if anything, this is an even sweeter revenge. Gilda emerges from the Duke’s chambers distraught and dishevelled, but full of compassion for the man for the man she now knows to be the Duke. They are interrupted by Monterone who, on the way to execution, regrets that his curse has had no effect on the Duke and his debauchery. In response Rigoletto swears vengeance on the Duke, both for himself and for Count Monterone.

Between the second and third acts, Rigoletto has been in contact with Sparafucile, determined as he now is to avenge his daughter and the Count’s. The Duke has been lured to a tavern on the outskirts of the city, occupied by Sparafucile and his sister (and co-conspirator) Maddalena, who is attractive enough to arouse the Duke’s interest and persuasive enough to lure him to the hut. The Duke arrives in high spirits and sings the opera’s most famous number, in which he claims that women are fickle and unreliable, thus justifying his own fickleness and unreliability. Outside the hut, Rigoletto forces his daughter to witness the Duke’s seduction of Maddalena as he professes love with the very same words he once used on Gilda. He orders his heartbroken daughter to flee the city; he will join her the next morning. However, Gilda stays outside the tavern. As a storm begins to rage, Rigoletto and Sparafucile settle on a price to kill the Duke and arrange that Rigoletto will return for the body at midnight. Unfortunately, Maddalena is now intrigued by the Duke, and convinces her brother to spare him, even suggesting that they kill Rigoletto instead. Ultimately they agree that if a stranger comes to the tavern seeking refuge from the storm, they will substitute that victim for the Duke. Overhearing this, Gilda decides to sacrifice her own life, thus she knocks on the door and meets her fate. Rigoletto then returns to collect the Duke’s body. As he prepares to throw the sack containing the corpse into the river, he hears the Duke’s voice in the distance, singing one of the most familiar tunes in all opera. Rigoletto rips open the sack to find Gilda. Struggling to breathe, she begs him to find forgiveness, and promises she will be watching over him in heaven. But with her last breath the Count Monterone’s curse is fulfilled.