Act I The goddess Diana rules over an island realm where all her devotees have sworn to remain chaste. There is a tree on the island with golden apples that turn black whenever an unchaste person comes near. Diana has abducted the shepherd Doristo to her island to guard the tree. Amor, the androgynous god of love, wants to destroy Diana’s cult of chastity. He gives Doristo a magic ring that will protect him from the tree’s power. Doristo has always wanted to be alone among women, so Diana and her nymphs suit him perfectly. To punish the shepherd for his amorous desires, Diana turns him into a plant. – Amor undoes Doristo’s transformation with the help of the two shepherds Endimione and Silvio. The three men now plan a lovers’ meeting with the three nymphs Britomarte, Clizia and Cloe behind Diana’s back. In the meantime, Amor challenges Diana to give up her cult of chastity, cut down the tree, and submit to him. When Diana refuses to surrender to the tyrannical power of love, the god of love shows her what her three disciples have been doing. However, Diana still refuses to give up her cult of chastity. Amor now gives Endimione and Silvio, who are dazzled by Diana’s beauty, one arrow each: the one that wounds the goddess’s heart with his arrow will savour the joy of her love. Endimione’s arrow hits Diana’s heart. The unsuccessful Silvio swears revenge.

Act II The three men try to escape from Diana’s island, but are caught by the goddess. Endimione is to die on behalf of all three. But Diana, who has developed feelings for the first time, is unable to kill him. Clizia and Cloe, who now regret their disobedience, want to kill Endimione instead, but Silvio stops them. When, some time later, Diana finds Endimione asleep, she realises that she loves him. Amor turns Silvio, who cannot bear the fact that he failed to win Diana’s love, into the old priest Alcindo. In the meantime, Doristo is being hunted by the three women, having promised each of them that he would marry them. Amor rescues him from his predicament. Silvio, now a priest, calls everyone together and demands from Diana that she take her tree’s test of chastity herself. The goddess collapses and confesses that she has gone against her own commandment. Amor emerges as the victor and decrees that Diana should marry Endimione, Silvio should become a priest of love, and Doristo can live with the three women as the island’s guardian.