The eponymous garçonne or flapper is Monique Lerbier, an emancipated French woman who leaves home to escape a marriage of convenience to a man she does not love which her parents have forced on her. She then falls into all sorts of carnal temptations and artificial pleasures previously unknown to her. These include her being seduced into a lesbian love affair by a chanteuse.

Les parents de Monique Lerbier veulent, par intérêt, la contraindre à épouser un homme qu’elle n’aime pas. Elle quitte alors le foyer familial et succombe à toutes les tentations charnelles et plaisirs artificiels qui lui étaient jusque-là inconnus…