Act 1
The scene of the opera is Directoire Paris, 1794; the Reign of Terror is over, but Paris is still a dangerous place for opponents of the government. The heroine is a charming young florist called Clairette. She is the daughter of Madame Angot, a former market woman of Les Halles, who was famous for her beauty, her amorous adventures, and her sharp tongue. She died when Clairette was three, and the child was brought up by multiple adoptive parents from Les Halles and given a fine education at a prestigious school.

A marriage with Pomponnet, a sweet and gentle hairdresser, has been arranged for her against her wishes, for she is in love with Ange Pitou, a dashing poet and political activist, who is continually in trouble with the authorities. His latest song lyric, "Jadis les rois", satirizes the relations between Mlle. Lange – an actress and the mistress of Barras – and Barras's supposed friend Larivaudière. The latter has paid Pitou to suppress the song but Clairette gets to hold of it and, to avoid her marriage with Pomponnet, sings it publicly and is, as she expects, arrested so that her wedding is unavoidably postponed.

Act 2
Lange summons the girl to learn the reason for her attack and is surprised to recognize her as an old-school friend. The component loudly protests Clairette's innocence and says that Ange Pitou is the author of the verses. Lange already knows of Pitou and is not unmindful of his charms. He has been invited to her presence and arrives while Clairette is there and the interview is marked with more than cordiality. The jealous Larivaudière appears meanwhile and, to clear herself, Lange declares that Pitou and Clairette are lovers and have come to the house to join in a meeting of anti-government conspirators to be held at midnight. Clairette discovers that she does not enjoy a monopoly of Pitou's affections and that he is dallying with Lange.

The conspirators arrive in due time, but in the middle of proceedings, the house is surrounded by Hussars; Lange hides the badges of the conspirators, "collars black and tawny wigs", and the affair takes on the appearance of nothing more dangerous than a ball. The Hussars join gaily in the dance.

Act 3
To avenge herself, Clairette invites all of Les Halles to a ball, to which she lures Lange and Pitou by writing each a forged letter, seemingly signed by the other. At the ball Pitou and Lange are unmasked, Larivaudière is enraged, but realizes he must hush matters up to save Barras from scandal. After a lively duet in which the two young women quarrel vigorously, there is a general mêlée, ended by Clairette who extends a hand to her friend and declares that she truly prefers the faithful Pomponnet to the fickle Pitou. Remembering Madame Angot's amorous flights, Pitou remains hopeful that Clairette will take after her mother and may one day be interested in him again.