In this classic French satire, Louis, a convict, escapes from prison and takes on legitimate work, making his way up in the business world. Eventually becoming the head of a successful factory, Louis opts to modernize his company with mechanical innovations. But when his friend Émile finally leaves jail years later and reunites with Louis, the past catches up with them. The two, worried about being apprehended by police, long to flee the confines of industry.
Director Rosé and his opera company travel to Monte Carlo where they expect an engagément to perform at the opera house. During the boat trip Mario, the cheerful tenor, meets a girl hidden in his cabin. He helps her singing for her passage and soon Nicole is adopted by the whole troupe. Then at Monte Carlo the opera director has no intention to sign them. But he has an eye for beautiful women, so Nicole will try to persuade him to reconsider the offer.
A little mechanic and a delightful milliner love each other on the banks of the Marne. A schemer manages to make the mechanic her lover for a few days, but the contrite young man obtains forgiveness from his girlfriend, the only woman he loves.
