The action takes place in Gaul under the Roman occupation, and is centered on the triangular love affair between Pollione, the Roman proconsul of Gaul, Norma, his former companion, and the young Adalgisa. The background is the uprising of the Gallic people against the Roman occupiers, led by the Druid Oroveso.
Norma, the high priestess of the Druid temple, who had two children by Pollione, the Roman proconsul of Gaul, breaking her Druid chastity vows, discovers that her lover is now in love with her friend, the young Druid priestess Adalgisa. Norma tries to convince Pollione to give up Adalgisa and return to her, but he refuses. Norma publicly confesses her fault and is sentenced to death by fire. Pollione is convicted for pursuing Adalgisa in the temple and goes to the stake with Norma.