ACT I. The action takes place in ancient Gaul, under Roman occupation, where the Druid priestess Norma has fallen in love with a Roman official named Pollione and has secretly borne him two children. Norma is also the daughter of the Druids' leader, Oroveso.
As the action begins, Oroveso instructs his followers to go into the sacred forest and wait for Norma, who will signal the start of a planned revolt against the Romans. When the Druids leave, we find Pollione talking with the centurion Flavio. Pollione admits that he's no longer in love with Norma. His new romantic interest is the young acolyte Adalgisa, one of Norma's temple virgins. In the forest, a brass gong sounds. Pollione and Flavio leave, and a chorus announces the arrival of Norma.
As she cuts the sacred mistletoe, Norma sings the classic bel cantoaria "Casta Diva," a prayer to the goddess for victory over the Romans. The Druids follow Norma off, leaving Adalgisa alone to struggle with her emotions. She's torn between her love for Pollione, and her loyalty to Norma and her sworn duties. Pollione joins Adalgisa and begs her to elope with him to Rome.
The second scene takes place at Norma's home. She tells her friend Clotilde to hide her two little boys — the sons Norma had with Pollione. She's afraid of her ambivalent feelings toward them: "I love, and at the same time, hate, my children," she says.
Adalgisa pays a visit to Norma, asking to be released from her vows. She admits she's found love, though she doesn't say with whom. Norma is touched, remembering her own early days with Pollione. She agrees to release Adalgisa from her vows. But when Pollione arrives, the truth comes out. Norma realizes that he has betrayed her with Adalgisa, and Adalgisa learns that Pollione had pledged himself to Norma.
The act closes in a fiery confrontation. Norma curses Pollione, saying "My burning fury will engulf you like the wind and the waves." She orders Adalgisa to go with him. Adalgisa tells Pollione she'd rather die than desert her people.
ACT II. So far, Norma has come across as an unpredictable and even dangerous woman. Now, we find her sounding vulnerable and filled with doubt — and with a knife in her hand. She's still angry with Pollione and contemplates killing their two young sons. She raises her dagger over the sleeping children, but at the last moment backs down.
Norma calls for Adalgisa, and tells her to take the children and go live with Pollione in Rome. In a spectacular duet, Adalgisa says she won't do it. Instead, she'll tell Pollione of Norma's suffering, hoping that will move him to come back to Norma.
The scene changes to the sacred forest. Oroveso tells his Druid warriors to keep their anger for the Romans in check. They must wait for just the right moment to attack. They leave, and Norma is alone with Clotilde, who tells Norma that Adalgisa has failed to change Pollione's mind. He still loves Adalgisa, and plans to carry her off to Rome.
Norma is furious. "The traitor will go too far," she says, "but I will strike first, and Roman blood will flow like water." She runs to the altar and strikes the ceremonial brass shield, summoning the troops to battle.
In the commotion, an intruder is discovered within the Druid temple. It's Pollione. The punishment for any outsider entering the temple is instant death, and Norma is poised to kill him with the sacred dagger. But she hesitates, admitting to herself that she can't go through with it.
Taking Pollione aside, Norma offers him freedom if he will leave Adalgisa. But Pollione refuses, saying he'd sooner die. Norma says she'd be delighted to arrange for that and for the death of their two young sons, plus the death of his beloved Adalgisa. Pollione begs Norma to spare Adalgisa's life.
Suddenly, Norma calls for her people, announcing that Pollione won't be killed after all. Instead, there's a new victim, one who has betrayed her country. "I am the guilty one," she says and then calls for the sacrificial pyre to be prepared. The crowd tries to bring Norma to her senses, but she won't budge. She's determined to go down in flames. In her final words to her father, Norma admits that she is the mother of Pollione's children and asks the shocked Oroveso to protect them. Meanwhile, Norma's bravery revives Pollione's love for her. He steps to her side, and the opera closes as the two walk into the flames together.
- Courtesy of NPR