The neglected daughter of an industrialist who made his fortune in explosives supplies during the war and of a mother who was mostly concerned with herself, Monique Lerbier is a pretty blonde with generous but strong ideas and a hard character. She has chosen to be an atheist since her adolescence and does not tolerate injustice and social hypocrisy. She was to be married to an engineer, Lucien Vigneret. It was an arranged marriage, the dowry having to allow Vigneret to enter the capital of his father's company, which needed it to finance its business. But two weeks before the wedding, Monique surprises the fiancé with a mistress.