Manrico’s army has been defeated, and he and Azucena are being held captive in di Luna’s castle. Leonora has escaped and now comes to the prison to pray for Manrico’s salvation. When di Luna orders the execution of Manrico and Azucena at sunrise, Leonora offers herself to the count in return for her lover’s life; however, she secretly takes a slow-acting poison, sealing her fate.
In their cell, Manrico tries to comfort Azucena, who is terrified of the stake and the fire that await her. Leonora appears to tell Manrico that he is saved and urges him to escape. Understanding that she has promised herself to di Luna, he denounces her and refuses to flee. But the poison is already taking effect, and Leonora dies in his arms, just as di Luna arrives. He sends Manrico to his execution. Azucena cries out that her mother is avenged: di Luna has killed his own brother.