ACT I — The Duke's Palace, Mantua, mid-16th century
While at a party at his palace, the Duke of Mantua expresses his desire for an assignation with a young woman he has recently seen at church, but soon afterward he sets his romantic sights on seducing the Countess Ceprano. As the Duke and the Countess leave together, her husband is mocked and humiliated by Rigoletto, the Duke's jester. Pondering revenge on Rigoletto, Count Ceprano is interested to learn from the nobleman Marullo that Rigoletto keeps a woman in his home. The elderly nobleman Count Monterone interrupts the party to defend the honor of his daughter, who has been ravished by the Duke. Rigoletto mocks Monterone's anger, and the enraged father responds by cursing the Duke and his jester.
Outside the palace later that night, the assassin Sparafucile confronts Rigoletto. Rigoletto sends him away, but compares his own biting tongue to an assassin's sword. When he arrives home, he is greeted by his daughter Gilda, whom he has kept secluded there since the death of her mother. Rigoletto leaves Gilda in the care of her maid, Giovanna. Soon afterwards, the Duke, disguised as a student, sneaks into the house and tells Gilda that he loves her. Gilda, who has noticed the disguised Duke following her home from church, returns his affections, and they bid each other farewell.
Outside, Ceprano and a group of the Duke's courtiers are gathering to abduct Gilda — whom they believe to be Rigoletto's mistress — in order to gain revenge on the jester. The courtiers blindfold Rigoletto and fool him into letting them into his own house. They depart with Gilda. Rigoletto hears her cries and removes the blindfold, but he is too late to save her, and he is left alone to remember Monterone's curse.
ACT II — The Duke's Palace
Having discovered that Gilda is missing, the Duke laments losing her. However, he soon learns that she was abducted his own courtiers, and he excitedly leaves to see her. Rigoletto enters, searching for Gilda, but he is turned away by the unconcerned courtiers. Gilda enters and tearfully tells her father about her flirtation with the duke and her abduction. As Rigoletto consoles his daughter, he watches as Monterone is led towards his prison cell. Rigoletto swears to Monterone that the Duke's crimes against both of their daughters will be avenged.
ACT III — Sparafucile's house, by the Mincio River
Rigoletto brings Gilda to the home of the assassin Sparafucile, whom he has hired to kill the Duke. Gilda is forced to watch from the outside as the Duke, no longer disguised as her lover, seduces Maddalena, the assassin's sister. After sending Gilda away, Rigoletto finalizes his arrangements with Sparafucile; he will return at midnight to accept the body and dispose of it. Against her father's wishes, Gilda returns and listens as Maddalena begs her brother not to kill the Duke. Sparafucile initially refuses, but relents and tells his sister that he will kill whoever arrives at the inn before Rigoletto returns. Gilda decides to allow herself be killed in place of her lover, knocks on the door, and is stabbed by Sparafucile.
Rigoletto returns at midnight, and is presented with a body in a sack. As he leaves, he hears the voice of the Duke singing in the distance. He opens the bag to find the dying body of his daughter. She dies in the arms of her father, who cries that Monterone's curse has been fulfilled.