A film adaptation of the short story of the same name by Guy de Maupassant. The action takes place in the XIX century. Franco-Prussian War of 1870. A group of French bourgeois leaves in a stagecoach from Rouen occupied by Prussian troops. Along with them comes one attractive demimonde lady. The only way to get out is to persuade her, nicknamed "Ball-of-Fat" a la "Boule-de-Suif" to satisfy the lust of the head of the gendarmerie...

A successful young journalist goes to a small industrial city in order to understand the written complaints of a certain girl. When he met the author of the letters and the girl whom she had slandered, he didn't immediately understand the complexity of the situation and the measure of responsibility to those whom he was obliged to protect...