Kate (Meg Ryan) is a fastidious and wholesome history teacher living in Canada with her fiancé, Charlie (Timothy Hutton), who is a doctor. While waiting for her Canadian citizenship to come through, Kate has been busy planning their wedding and the purchase of their first house, complete with a white picket fence. Charlie urges Kate to accompany him to Paris for an upcoming business trip, but she declines due to her fear of flying and her general intolerance for cheeses, secondhand smoke, and the French.
Kate’s plans for the future are interrupted by a drunken phone call from Charlie who informs her that he has fallen in love with a beautiful French “goddess” named Juliette (Susan Anbeh) and that he will not be returning. Determined to win him back, Kate boards a flight to Paris, despite her fear of flying, and is seated next to a crude Frenchman, Luc Teyssier (Kevin Kline), whose every word during the seven-hour flight seems to annoy her. Luc is a petty thief who is smuggling a vine cutting and a stolen diamond necklace into France hoping to use both to start his own vineyard. Despite the uncomfortable and sarcastic banter throughout the flight, Kate, with the help of a few drinks, is able to tolerate her “rude” and “hygiene deficient” seating partner long enough to arrive safely in Paris. Before deboarding, however, Luc sneaks the vine and necklace into Kate’s bag, knowing she would not be searched at customs, and then offers Kate a ride into Paris.
At the terminal, Luc is spotted by Inspector Jean-Paul Cardon (Jean Reno) who insists on giving Luc a ride during which he searches his bag. The inspector feels protective of Luc who once saved his life. Meanwhile, Kate makes it on her own to the Hôtel George V where she encounters new levels of French sarcasm and rudeness from the concierge. While waiting in the lobby to confront Charlie, she meets a petty thief named Bob. When she finally sees Charlie and Juliette kissing in an elevator, Kate faints, and Bob steals her bag. Luc arrives, steals a car, and together they track down Bob and the missing bag.
Upset at having lost all her money and her passport, Kate argues with Luc and they go their separate ways. Kate soon learns that Charlie and Juliette are headed south to Cannes to meet her parents before the wedding. Meanwhile, after realizing the necklace is still in Kate’s bag, Luc tracks her down, offers to help her “win back Charlie”, and together they board a train to Cannes. Along the way, Luc attempts to search her bag but is unsuccessful. After the lactose intolerant Kate samples some of the 452 official government cheeses of France, she becomes sick and they get off the train at Luc’s hometown of La Ravelle in Paulhaguet. They stay at Luc’s family home, surrounded by a beautiful vineyard where Kate learns about Luc’s past and how he gambled away his vineyard birthright to his brother in a single hand of poker. Kate also learns that Luc knows a lot about wines. Gradually the two grow closer, and after Luc searches the bag and comes up empty, he agrees that he will help Kate.
At Cannes, the inspector approaches Kate and urges her to convince Luc to return the stolen necklace anonymously to avoid jail. Luc, who is planning to sell the necklace at Cartier, agrees to Kate’s plan to have her sell the necklace. Meanwhile, Luc is busy instructing Kate on how to win back her lost fiancé. To make Charlie jealous, Luc pretends to be Kate’s lover when they meet Charlie and Juliette on the beach, and the deception works. At dinner, Charlie apologizes to Kate and later tries to seduce her in her room, but she rejects his advances, realizing she no longer wants him—she is in love with Luc. Meanwhile, in an effort to “ensure victory” for Kate, Luc attempts to seduce Juliette, but she walks out after he calls her “Kate” by mistake.
The following morning at Cartier, Kate returns the stolen necklace to the inspector and purchases a Cartier check for $45,782 with her own savings to create the illusion that she actually sold the necklace. After giving the check to Luc, Kate leaves for the airport pretending to meet Charlie. Soonafter, the inspector approaches Luc and reveals the charade and all that Kate has done for him. When he realizes that Kate will not be returning to Charlie, Luc rushes to the airport, boards the airplane, and confesses that he’s in love with her and wants her to stay with him. Sometime later, Luc and Kate embrace each other in their beautiful new vineyard.