It is night in the sacred forest and Oroveso, the high priest, and the Druids wait for the moon to rise. It is then that Norma, his daughter and high priestess, is expected to cull the mistletoe, a ritual signaling the revolt against their Roman oppressors. Nearby, the Roman proconsul Pollione and his lieutenant, Flavio, lie in wait. Their presence in the forest is forbidden, but Pollione is searching for Adalgisa, a novice at the temple of Irminsul and his new love. Flavio rebukes him for so easily discarding his former lover, Norma, who has broken her vow of chastity by secretly giving him two sons. The approach of the Druids causes them to retreat into the forest. Oroveso and the others call for vengeance against the Romans, but Norma tarries — fearing for Pollione's safety, she declares that the time for an uprising has not yet come. Publicly Norma proclaims the proconsul shall be punished, but privately she reveals her steadfast devotion to him.
After the Druids leave, Adalgisa enters and is soon joined by Pollione. Also having broken her oath as a priestess, Adalgisa is troubled and has her doubts over this dangerous love affair. She is eventually persuaded by Pollione to follow him to Rome, and they agree to meet the following evening.
Inside her remote dwelling Norma confides in Clotilde — she suffers at both the sight and the absence of her two children and suspects they are the reason why Pollione will not take her to Rome. Adalgisa enters and confesses her transgression. As she describes her first clandestine meeting in forest, Norma recalls her own very similar encounter with Pollione and is ready to forgive but soon discovers they have both been seduced by the same man. Pollione enters, and Norma immediately condemns his lack of fidelity. As Pollione urges Adalgisa to leave with him, she resists, preferring to die so that he will return to his family.
To punish Pollione, Norma is about to murder her children, but moved by their innocence, can't bring herself to do it. Instead she contemplates suicide, and after summoning Adalgisa, implores the young woman to marry Pollione and take care of the children after her death. Moved by Norma's sacrifice, Adalgisa counters that she will go to Pollione and convince him to return to the mother of his two sons.
In the forest the Druids are still aggravated by the Romans, and Oroveso has learned a far more severe commander will be taking Pollione's place. Clotilde brings news that Adalgisa has been unsuccessful in her suit, and Pollione intends to steal her away that evening. Norma's fury comes to a boil as she incites the warriors to battle.
Pollione has been discovered in the cloister of the novices and must be put to death as a result of the sacrilege. Norma interrogates him alone — if he will abandon all thoughts of Adalgisa, she will spare his life. When he refuses, she threatens to kill their children and burn Adalgisa alive for breaking her vows. He asks only to die.
Before Oroveso and the Druids, Norma proclaims that a priestess has been unfaithful and must be ritually sacrificed and, to everyone's surprise, announces that it is her. Norma implores her father to always care for her children and continue to hide them from the barbarians. As she mounts the pyre, Pollione, moved by her nobility and courage, ascends into the flames with her.
Courtesy of The Minnesota Opera