ACT I - THE DUEL
Scene 1: Aragon: a hall in the palace of Aliaferia, in Saragossa
The followers of the Count di Luna keep watch as he makes his nightly vigil under the windows of Leonora, one of the queen's ladies in waiting, whom he loves.
Ferrando, the captain of the guard, keeps his men awake by narrating a terrible happening of 15 years ago: an old woman, accused of casting the evil eye over the count's brother, was burnt at the stake. The subsequent disappearance of the boy, followed by the discovery of a child's skeleton in the ashes, led to the conclusion that the woman's daughter, who was present at the burning, had thrown him into the flames to avenge her mother. She was never found, but Ferrando swears that he would recognise her. As he relates how the witch has continued to haunt the castle, the soldiers are seized with superstitious terror.
Scene 2: The palace gardens
Leonora loves not the count, but the troubador Manrico. As she waits for him she tells her companion Ines how she first saw him at a tourney and loved him. She rejects Ines' warning of the dangers of her infatuation with the stranger. They retire and the count appears, his love-lorn musings interrupted by the sounds of Manrico's lute and serenade. In the dark Leonora mistakenly embraces the count, Manrico reproaches her and she explains the error.
The count confronts Manrico, not only as his rival, but as a follower of the rebellious Count of Urgel; and they rush off to fight a duel.
ACT II - THE GIPSY
Scene 1: A gipsy encampment in Biscay
As the gipsies sing and work at their anvils, Azucena broods on the fate of her mother, burned as a witch.
She explains the circumstances to Manrico (who had left her at an early age to pursue his ambitions and was thus ignorant of the story), going on to tell him how she had intended to avenge her mother by burning the count's son, but had become confused and killed her own child instead. In answer to Manrico's puzzled question about his identity, she assures him that he is indeed her own son - the horrible memory caused her mind to wander and she did not know what she was saying. She reminds him that she has always loved him and has just nursed him back to health after he was wounded in a battle against the count's forces. The battle had taken place just after the duel in which Manrico had spared the count's life, as a voice from heaven seemed to command him. Azucena urges him to strike without hesitation if the occasion arises again.
A message is brought that Leonora, believing Manrico dead, is about to enter a convent. Brushing aside Azucena's pleas that he is too weak to travel, he rushes off to prevent Leonora from taking the veil.
Scene 2: Outside the convent
The count has come to abduct Leonora, but Manrico's followers defeat his and rescue her.
ACT III - THE GIPSY'S SON
Scene 1: Outside the fortress of Castellor
As the count lays siege to the fortress, which is under Manrico's command, Azucena is found wandering near the camp and brought to the count, accused of spying. Ferrando recognises her as the woman responsible for the death of the count's brother and in terror she cries to Manrico to save her. Realising that she is Manrico's mother, in addition to her crime, the count prepares to execute her.
Scene 2: Inside the fortress
Manrico and Leonora are preparing for their wedding when Ruiz brings the news that Azucena is about to be burnt at the stake. Manrico rushes off to rescue her, explaining to Leonora that his mother's claims outweigh hers.
ACT IV - THE EXECUTION
Scene 1: The Aliaferia palace
Ruiz brings Leonora to the tower where Manrico is imprisoned, having been captured in his vain attempt to save Azucena. Monks intone the miserere as Manrico laments that death is slow in coming. Leonora pleads with the count for Manrico's life, offering herself in exchange. As he joyfully accepts her bargain, she takes poison, intending to leave him only her dead body.
Scene 2: Inside the dungeon
Manrico soothes Azucena, who is terrified at the idea of fire, and she falls asleep comforted by the idea that they will soon return to their mountain home.
When Leonora tells Manrico that he is free, he suspects the price she has paid and upbraids her, realising only as she collapses at his feet, that she is dying to save him. The count appears as she breathes her last, and realising that he has been deceived, orders Manrico's immediate execution. Azucena wakes too late to prevent this, but is able to avenge her mother by telling the horrified count with her dying breath that he has just killed his brother.