This comic-opera takes as its starting point a poem by Jean-Baptiste Cresset about a parrot, Vert-Vert, brought up by nuns, but who has inadvertantly learnt inappropriate language from the boatmen on the Loire. The nuns restore the parrot to a virtuous life and spoil him (literally) to death.
Offenbach takes up the story at this point, where Vert-Vert has been the favourite pet in a girl's convent school, but is alas now deceased from constipation. He is buried with due honours in the school garden attended by Mimi, Bathilde and Emma together with Valentin (the nephew of the headmistress Mlle Paturelle) with the assistance of Binet, the school gardener.
Valentin is now also given the nickname Vert-Vert and becomes the pet of the schoolgirls, just like his predecessor! And like the parrot he falls into bad company (a drinking party of dragoons) and learns some inappropriate oaths which shock the nuns.
Travelling to Nevers with Binet, Valentin comes across two dragoon officers, the Comte d'Arlange and the Chevalier de Bergerac flirting with the theatre singer La Corilla. By coincidence, the two nobles have recently married (in secret) the young ladies, Bathilde and Emma.
Valentin is entranced by La Corilla, and when she finds that he has a fine voice, she persuades him to partner her in a forthcoming opera, since her leading man has caught cold. (He had been thrown into the river by Valentin after an earlier altercation).
Meanwhile, Mimi has dressed as a man, and followed Valentin to Nevers. She is understandably upset by his attraction to La Corilla, but manages to save him from a fate worse than death with the help of the two noble dragoons. In turn, Mimi and Vert-Vert help them to become reunited with their young wives, accidentally interrupting a tryst between Mlle Paturelle and Baladon, the dancing master, to whom she too is secretly married.
At last everything is resolved in Offenbach fashion!