By 1810, the girls, Blanche-Marie and Marie-Blanche, have grown up together, believing themselves to be twins, and have gone to school under the military Mlle. Herpin. Aristide, the Michus' clerk, is in love with one of the girls but is not sure which. The Marquis des Ifs, now a general, sends Bagnolet to find his daughter, whose hand he has promised to lieutenant Gaston Rigaud, an officer who saved his life. It turns out that Gaston is Mlle. Herpin's nephew, and while visiting his aunt, the girls meet the handsome lieutenant, and both are enchanted. Bagnolet finds the Michus. They are embarrassed at being unable to say which of the girls is the general's daughter.