The nymph Galatea and the shepherd Acis are in love. The shepherd, Damon, advises them both. Meanwhile, the monster Polyphemus is jealous and threatens Acis, while Coridon, another shepherd, advises him against violence. Polyphemus, however, crushes Acis with a massive stone. In response the half-divince Galatea uses her powers to turn him into a fountain.