García was the younger son of Count di Luna. One night an old gypsy woman was discovered staring at the infant boy in his cradle. Although she was chased off, the child developed a serious fever which was taken as proof that the old gypsy had put a curse on him. She was captured and burned at the stake. Soon after, García disappeared and a search led to the discovery of the charred remains of a child where the old gypsy had been burned. All but his father were convinced the young García had perished. On his deathbed, Count di Luna exacted a sacred oath from his elder son, the present Count di Luna, to continue the search for his younger brother. Although fifteen years have passed, the young count still honors his father’s request.
The old gypsy’s daughter, Azucena, watched her mother die in agony and heard her scream, “Avenge me!” Azucena then abducted the Count di Luna’s infant son, García, intending for him the same horrible death her mother had endured. Carrying her own young son as well, she brought García to the still-burning stake, but as she was placing him in the flames, she hesitated, moved to pity by the boy’s crying. In her confusion and anguish at remembering her mother’s screams, she grabbed the child and, unable to watch, threw him into the flames. As her torment subsided, she discovered to her horror that she had put her own son to death. She decided to raise the di Luna boy as her own and named him Manrico. For years, her mother’s scream, “Avenge me!” has echoed in her mind and heart.
Civil war has broken out in Spain between the Prince of Aragon and the rebel Count Urgel. At the castle of Count di Luna, commander of the Aragon troops, soldiers are keeping watch. Ferrando, a captain in Count di Luna’s army, tells the sentries and servants to be alert: the count fears that a troubadour sometimes seen in the garden is a rival for Leonora, the woman he loves. Ferrando relates the tale of the count’s younger brother, García di Luna, noting that the spirit of the old gypsy continues to haunt the palace. He insists that even after all these years he would still recognize her daughter, Azucena, the one who abducted the boy.
In the palace gardens, Leonora, a lady-in-waiting to the Princess of Aragon, tells her maid Inez about a knight she met once at a tournament; he has returned and has been serenading her. Leonora professes her love for the mysterious troubadour. After the women depart, Count di Luna goes to the balcony of his beloved Leonora. The troubadour’s serenade is heard in the distance. Leonora rushes out and greets the count, mistaking him for the troubadour. The mysterious troubadour finally reveals his identity: he is Manrico, leader of the rebel forces. The count challenges Manrico to a duel.
Manrico has been wounded in a battle with di Luna’s men. He is in the gypsy camp, being tended by his mother, Azucena. Azucena is haunted by memories of her mother’s death. She relates the story, and reveals to Manrico that she mistakenly burned her own son to death. Manrico is confused by this: who is he then? Azucena tells him that she was distraught, and not making sense. She asks Manrico about the duel, and he tells her that he could have killed di Luna, but a mysterious power stayed his hand. Azucena demands that her “son” kill Count di Luna if they meet again, hoping this will appease her mother’s cries for revenge. Manrico discovers that Leonora, believing him killed in battle, is going to enter a convent. He rushes off to find her.
Count di Luna determines to abduct Leonora before she enters the convent. As he is about to do so, Manrico arrives, defeats di Luna and his men, and takes Leonora with him to his military stronghold.
Di Luna determines to attack the fortress of Castellor, where Manrico has taken Leonora. Ferrando brings in Azucena, who has been captured nearby. Her reaction gives her away when she discovers the identity of di Luna, and Ferrando recognizes her as the gypsy who supposedly burned García to death. As she cries out to her “son” Manrico for help, Count di Luna revels in the prospect of revenge, and orders her to be burned at the stake.
Leonora and Manrico are about to be married when news arrives of Azucena’s plight. Manrico gathers his army and rushes off to save her.
Having lost the battle with Di Luna, Manrico awaits execution in the tower prison. Leonora, determined to save his life at any cost, promises herself to di Luna in exchange for Manrico’s life. He agrees to the bargain. While arranging for the troubadour’s release, he fails to see Leonora swallow a deadly poison.
Azucena, suffering increasingly from hallucinations and terrors, is comforted by Manrico. Leonora enters to report he is free to go—but not with her. Manrico is outraged by the bargain she has made, but it soon becomes clear that she is dying. Furious over Leonora’s betrayal, the count orders Manrico’s death. Forced to watch his execution, Azucena reveals to di Luna that he has just killed his own brother, García. The old gypsy’s revenge is complete.