Capricious small-town girl Juliette and barge captain Jean marry after a whirlwind courtship, and she comes to live aboard his boat, L'Atalante. As they make their way down the Seine, Jean grows weary of Juliette's flirtations with his all-male crew, and Juliette longs to escape the monotony of the boat and experience the excitement of a big city. When she steals away to Paris by herself, her husband begins to think their marriage was a mistake.

The itinerant musician Lampluche, having found a musical score on the banks of a river and a full wallet, was taken to the neighboring town for the famous composer Maxence Leroy. The inhabitants of the small town only dream of music, so Lampluche is very well received. But Maxence Leroy arrives in the city.

A slapstick comedy centered on two neighboring republics, Crogandia and Miremia, and the various disasters that befall the ceremonial unveiling of a statue, the launching of a ship, and the crash-landing of a Miremian pilot in Crogandian territory.