An American in Paris lives by sponging off his working friends, and throws a party using borrowed money when his rich American aunt dies, believing firmly in his horoscope.

Young provincial Charles arrives in Paris to stay with his cousin Paul while studying law. Paul is a decadent, bohemian pleasure-seeker who shows the meek, diligent Charles the thrills of city life. When Charles falls for Florence, one of Paul's acquaintances, relationships begin to shift.