Act I, Scene 1
In the ducal palace a lavish party is in progress and the Duke of Mantua soon declares his personal creed of taking pleasure as and when he can find it. His jester, Rigoletto, offers an ironic commentary on the Duke's actions as the latter flirts with the Countess Ceprano. Incensed by Rigoletto's mockery, Count Ceprano arranges for a number of courtiers to meet at his dwelling that evening. Monterone, whose daughter has been seduced by the Duke, interrupts the gathering; also openly derided by Rigoletto, Monterone issues a curse on the Duke and his jester.
Act I, Scene 2
In a blind and dingy alleyway, as he returns home, Rigoletto, still tormented by Monterone's words, is accosted by a professional assassin, Sparafucile. Sparafucile enigmatically warns the jester that he may soon need his services to deal with a rival. Arriving home, Rigoletto is met by Gilda, his daughter, whom he jealously guards, keeping her hidden for her own protection. Rigoletto speaks of Gilda's mother to her yet, though she longs to know more, he refuses to tell and leaves her in the safe-keeping of his duenna, Giovanna. But the Duke has already spied Gilda at church and now appears, ready to claim her, despite his discovery that she is Rigoletto's daughter. When Rigoletto has finally gone, Mantua steps forward with a passionate avowal of love, easily reciprocated by Gilda herself. Footsteps are heard and they are those of the courtiers gathering at Ceprano's house opposite. The Duke vanishes and Rigoletto comes out again. The gang trick him into being blindfolded, whereupon they carry off Gilda. By the time Rigoletto fully appreciates the power of Monterone's curse it is too late.
In a chamber of the palace, the Duke worries that he may have lost Gilda, for when he returned to Rigoletto's house later last evening she was nowhere to be found. The courtiers soon cheer him up, however, by revealing they have brought Gilda to him. A distraught Rigoletto appears, searching anxiously for his daughter. He realizes she must be with the courtiers and curses them. Gilda herself materializes, full of remorse, despite the abduction having taken place against her will. Monterone is brought through the room on his way to prison; and Rigoletto promises him he will soon be avenged, as he plans the dastardly Duke's downfall.
On the banks of the river Mincio, Rigoletto, now having enlisted the help of Sparafucile, brings Gilda to a tavern where they are observe the Duke in action. The new object of the Duke's affections is Maddalena, Sparafucile's sister, and apparently in on the plot. As the philandering Duke proceeds in his wooing, Gilda despairs. Rigoletto sends her home and then arranges with Sparafucile to return at midnight for the Duke's body. Gilda goes but soon returns in disguise to hear Sparafucile and his sister arguing: Maddalena has fallen for the Duke and now wants to spare his life. Sparafucile replies that if anyone else calls at the inn before Rigoletto's return, he can be murdered and substituted instead. Gilda resolves to sacrifice herself and enters the tavern. Punctually at midnight, Rigoletto comes back to collect his victim. He gloats over the booty, until he hears the distinct voice of the Duke himself. Tearing the sack open, he discovers Gilda, stabbed and about to die. She tries to comfort her father but it is too late: Monterone's curse has been fulfilled.