Marceline is pretty but inconstant. She has a brother, eccentric as well as invading, who serves as a go-between between the fickle young woman and her lovers. She has been the mistress of Richard for a while when Jeff, an engaging but but unrepentant dreamer, falls madly in love with her. Marceline first turns him down but finally accepts him after she breaks up with Richard. But the coquette has not given up her escapades to which the young florist, nicknamed "Jean de la Lune" for his naivety, turns a blind eye. Little time after their wedding , Marceline becomes infatuated with the good looks of a superficial young man, Alexandre. But Jeff, who has developed a fondness for Jean, intervenes to save the couple.

Eugène, who works for Radio-Europe, is a bit dim-witted. He lives in a block of flats whose caretaker is Madame Motte, and the lady is in love with the young man. Just for laughs, Eugène's friends circulate on the air the rumor that Eugène has inherited millions of francs. It does not take long before a swarm of 'friends' start mixing with him. After a while, considering that the joke has lasted long enough, the jokers reveal the truth. Eugène immediately loses all his 'friends' but not he girl he loves. Even better, Eugène actually inherits a big sum of money. He who laughs last laughs best!

The war will separate the members of the Valon family, two sons Alexandre and Antoine being prisoners, while the youngest Gilbert enters the secret army. Only their sister, Denise, will stay on the farm with her grandfather and grandmother. The Germans invade the free zone.