Owen Wilson is a very successful Hollywood screenwriter who looks on what he does as lucrative hackwork. While full of self-doubt, he's been working on a serious novel he hopes might prove to be good. His gorgeous fiancée (Rachel McAdams) wishes he'd outgrow that nonsense. Her father wishes he weren't a dang liberal. ("You always take the side of the help. That's why Daddy says you're a communist," McAdams tells him. Later her father asks him to "say hello to Trotsky."). Her mother thinks he's a bit cheap, and "Cheap is cheap."
They're all in Paris because her father is concluding a business deal (not that he approves of the French, he makes clear), and the rest are along for the food and the shopping and the tourist sites. Except for Wilson, that is, who simply loves the city and how it has served as an inspiration for so many artists and writers, particular in its golden age of the 1920s.
Which is where Wilson miraculously winds up when he discovers a way to slip back into the past if he's in a certain place on the stroke of midnight. Suddenly he's conversing with Scott and Zelda Fitzgerald and hanging out with Cole Porter and listening to pompous advice from Ernest Hemingway. When Wilson asks Hemingway if he'll read his manuscript Hemingway tells him he shouldn't get advice from another novelist who will be jealous if it's good, but he offers to pass it on to one of the few people whose opinions he trusts, Gertrude Stein. All the historical personages are affectionate caricatures. At one point when Wilson describes his troubles to three surrealists at his table, Man Ray exclaims, "I see a photograph," Luis Buñuel cries, "I see a film," Wilson laments, "I see insurmountable problem," and Salvador Dalí declares, "I see rhinoceros!"
This is one of Woody Allen's best films, a romantic comedy in which the real heroine is the city of Paris. (Incidentally, the tour guide at the Rodin museum is played by Carla Bruni, the wife of the President of the French Republic.) I recommend it highly.