The Metropolitan Opera: Norma.

Deep in a forest where druids and warriors seek revenge against the conquering Romans, Norma is scorned by the Roman proconsul Pollione, with whom she has two children. Her kindness turns to fury when she discovers that Pollione has taken Adalgisa, a novice priestess, as his new lover. When Pollione loses his high rank in the army and is offered as a sacrifice, Norma promises him freedom under one condition.