The writer Pierre Carot became rich and famous with his book "Life as a Couple", which was based on the loving relationships of four couples. Now he's setting up his will and wants to leave his wealth to the couples among the four, which are still as deeply in love - if any: else, his companions get the money. He sends them out to visit the couples and test their love.
Noël Bienvenu, owner of a career, is a widower and lives with his parents. His son Bastien, whom he despises, was sentenced to six months in prison for theft. Noël goes to see a dying friend, Romieux, who asks him to take care of his daughter Marthe, who has settled in Paris (Batignolles district). Noël goes there and discovers that Marthe is destitute (her lover Gaston being an incarcerated mobster): he then offers her to come and live with him and soon, marries her.