Il ne faut jurer de rien ! (2005)

In Paris in 1830, during the final days of Charles X’s reign, Baron Haussmann (Jean-Luc Porraz) dreams of rebuilding the city. The idea of creating department stores is in the air, and Georges Van Buck (Gérard Jugnot), the owner of a fashion boutique, is thinking of expanding his business. But he feels that neither the long nor the short version of his name, written on a shop sign, sounds right. His employees tell him about a very large order—3,000 francs—placed by the Baroness of Mantes (Marie-France Santon). But she is short of money and wants to pay in installments. Unwilling to risk not being paid, Georges goes to see the baroness. She tells him that she cannot pay upfront and that the ball is meant to find a suitable match for her daughter, Cécile (Mélanie Doutey). Suddenly, Georges has an idea: why not bring the two families together? That would let him add the letters DM to his sign, which would look very impressive. But for that to happen, his nephew Valentin (Jean Dujardin) and Cécile would have to fall for each other. The baroness agrees to let Van Buck introduce his nephew to her. Georges finds Valentin in a brothel, “Le Sérail,” where he has run up substantial debts. To win his nephew’s goodwill, he pays them off for him, including some imaginary debts. But when his uncle starts talking about marriage, Valentin tells him that, on principle, he categorically refuses to marry. A gambler and full of confidence, Valentin bets 10,000 francs that he will have seduced Cécile by midnight the following day, with a kiss as proof. If he succeeds, he will not have to marry and will receive the money. His only condition is that everything happen incognito and that his uncle not introduce him to the baroness as his nephew. The next day, Valentin arrives at the Mantes estate. He pretends to have taken ill after a carriage accident. He briefly “comes to” and introduces himself to the baroness as Prince Frédéric of Habsburg, then faints again. He is carried to a bedroom and put to bed, where Cécile looks after him. Valentin thinks he will quickly win her over, but she avoids him. When he enters her room at night and gets into bed beside her, she drives him off at swordpoint. The next day, Cécile has disappeared, and Valentin finds her at a nearby fairground. They compete at various stalls, but Valentin’s attempts at seduction fail. The young man thinks he has lost his bet when the girl calls for help. Three cutthroats are attacking her, and Valentin manages to subdue them; she is grateful to him. However, he does not get the kiss he needs to win the bet. He arranges to meet her at nine o’clock that evening in the estate’s park, certain that he will win the challenge before the deadline. But Valentin is gradually falling in love with Cécile. Georges says so plainly, but Valentin replies that he knows nothing about love or marriage. When Georges visits the baroness, he notices that Cécile has twigs in her hair, a sign that she has been to the park. He admits to the baroness that Valentin is his nephew and reveals the whole scheme and the bet, but explains that the young man’s feelings for Cécile are sincere. The baroness sends him away, and Valentin withdraws, but makes sure to meet Cécile at the door and gives her a rendezvous in Paris, at an address without telling her what kind of place it is. Afraid that Cécile will not be there for her ball, the baroness locks her in, but Cécile persuades the priest (Patrick Haudecœur) in the adjoining room to help her escape. A carriage hired by Valentin is waiting for her at the estate gates. Valentin and Georges go to Le Sérail, the address the young man gave Cécile. Valentin bets the people there on whether or not Cécile will come in. Realizing where she is supposed to meet him, Cécile hesitates for only a moment before entering. Everyone is wearing masks, and she searches for Valentin. He eventually appears and tells her that she was merely the subject of a bet, and that he only wanted to have fun with her and seduce her. But Cécile still loves him. Valentin gives in, confesses that he loves her too, and they kiss shortly before midnight. The next morning, the baroness is astonished to find a crowd of unexpected guests arriving at her estate for the ball: all the regulars and residents of Le Sérail have come to throw a wild party. But while Cécile and Valentin are making plans for their life together, Jean-Guillaume (Raphaël Personnaz), a handsome young aristocrat who has been injured, appears in the entrance hall. Cécile is not indifferent to him, and goes back to dancing with Valentin—but nothing is certain.