The gardens outside Léontine’s château, late 1770s.

Valcour has been hopelessly in love with Léontine, a beautiful young widow, for years. With the help of his friend Ophémon, Valcour has been showering Léontine with gifts, flowers, and love letters. He has done so anonymously; Léontine felt lost after her husband’s death and Valcour is certain that she has no interest in romance. He tells Ophémon that he has lost all hope of winning her affections, while Ophémon responds that it is time for Valcour to reveal his secret.

Léontine arrives and asks Valcour to settle a dispute she is having with her friend Dorothée. The anonymous lover has sent Léontine a bouquet of flowers along with a letter asking her to carry it at a wedding later that day; if she doesn’t, he will take it as a sign that he should leave her alone. Dorothée thinks that it would do no harm for Léontine to accept the flowers. Léontine, conflicted over the request, says she does not wish to hurt her secret admirer, but doesn’t want to lead him on either. Valcour convinces Léontine to carry the bouquet.

Jeannette and Colin, a young peasant couple about to be married, express their thanks to Léontine for making their wedding possible. They hope that everyone might be as filled with love and joy as they are. Léontine is surprised, but this wedding seems to be another one of the festivities the anonymous lover regularly organizes for her. The guests are enthusiastic to prepare the wedding and the joy is contagious.

Dorothée, Léontine, and Valcour find themselves alone for a moment as the other guests start the festivities. Valcour tells Léontine that the anonymous lover might very well be watching them nearby, and convinces her to call out to him to reveal himself. When she does so, Valcour overdramatically answers that he himself is the tormented anonymous lover. Léontine feels overwhelmed, even dizzy. Valcour and Ophémon quickly try to convince Léontine that it was all in jest, while Jeannette and Colin are sympathetic to Léontine’s obvious emotional distress.

Later that evening, Valcour reaffirms his resolve to make Léontine fall in love with him.
Separately, Léontine laments that Valcour is unlikely to understand her feelings, and wishes she could unburden her heart to him. Ophémon arrives and improvises news that he has spoken to the anonymous lover. Pressed by Léontine, Ophémon says the anonymous lover worries that it would be impossible for Léontine to love him, but wishes to reveal his identity anyway. Léontine agrees to the meeting.

As she awaits the arrival of her secret admirer, Léontine reflects that her heart is now full of unexpected passion. When Valcour shows up, explaining that he is just there to be her supportive friend, Léontine pleads with him to leave before the anonymous lover arrives. As Ophémon and Dorothée listen in secret, Léontine and Valcour finally confess their love for each other. Unable to contain their excitement, Ophémon and Dorothee tumble into the room and reveal a secret love of their own. Dorothée sings an ode to love, laughing at the unlikely scene.

Both couples join the festivities and celebrate with a double wedding.