Gaspard lives in Paris and has an ex-wife and a career as a well-respected novelist. However, he is thoroughly bored with his life and is also short of funds for paying alimony. He decides to go to Brittany to visit his goofy brother and renew his ongoing affair with his brother's wife. Paul is equally at loggerheads with his life as a schoolteacher and is tired of forever adoring his wife and getting a cool response from her in return. On a whim, the two men decide to change places. Gaspard will stay with Paul's wife and will take over his teaching duties, Paul will go to Paris, take over Gaspard's apartment, make the acquaintance of his current girlfriend, and will attempt to make a go of it as a novelist. In this comedy, the switch is a great success, but that is only the beginning of the brothers' adventures.
Source : allmovie.com