Emile is a steelworker in a car factory ;a confirmed bachelor going on fifty, he leads a peaceful life .One night, he is woken up by a burst of machine gun fire. The cafe in the corner of the street has been burglarized.A distraught young girl rushes into his apartment building and hides in his room .When the police make a search, he makes her out to be his lover for the night.Madeleine tells her about her sad past : she has severed all links with her parents ,she's an unwed mother and in the underworld's clutches. Emile sends his protegee to old mommy Dupont's place ,in the suburbs of Paris.
A beautiful and sophisticated teenager is placed in a regimented French girls' boarding school after her father apparently commits suicide over a business scandal. She immediately gains admirers -- a lustful middle-aged artist, a handsome young composer, a fellow female student -- as well as a jealous rival. With the help of her schoolmates, she attempts to elope with the composer, but the adults catch on to the plot, and she is locked into her room at night.
Lola Montes, previously a great adventuress, is reduced to being the attraction of a circus after having been the lover of various important men.
Sabine Gravières, married to Edouard, the High Commissioner for Criminal Youth, has a problem: Juliette, her daughter, is not only pregnant but she also refuses to marry Claude, the young man who got her pregnant. It is fair to say that the model set by Juliette's parents is far from ideal. Aware at last of the problem, Sabine decides to try and make it up with her husband.
The title of this French "reality" drama, which translates to Before the Deluge, is a play on Louis XVI's famous prognostication, "Apres moi, le deluge." Set in 1950, the film concentrates on five Parisian adolescents. Certain that the next war will herald the apocalypse, the youngster make plans to run off to a desert island and set up a new society. This, however, will require money, which is why the boys decide to pull off a "necessary" robbery. Idealism collapses in the face of cold reality, as the five youths suffer from the consequences of their actions. Avant le Deluge was one of a group of films cowritten by director Andre Cayatte and Charles Spaak which endeavored to explore the touchy social issues of the day: others in the Cayatte-Spaak canon include the euthanasia-themed Justice est Faite and the capital-punishment tract Nous sommes tous des assassins.