Valentine Dussaut (Irene Jacob) studies at University of Geneva and works as a part-time model. She regularly attends ballet classes. She calls her possessive boyfriend in London and plans to meet him. During her part-time job as a model, she poses for a chewing-gum campaign and the photo selected is one of her looking very sad. While walking back home, Auguste (Jean-Pierre Lorit), a student neighbour of Valentine’s, drops his textbooks and one book falls open at a particular chapter of the Criminal Code, which he notes. Driving back to her apartment, Valentine is distracted and accidentally hits a Malinois dog. She tracks down the owner, a retired judge, Joseph Kern (Jean-Louis Trintignant), who seems unconcerned. Valentine takes the dog, Rita, to a veterinarian, where she learns that the dog is pregnant. She overcomes the sexual advances made by the ad company’s photographer. Later, money is delivered to her apartment from an unnamed sender.
Out for a walk the next day, Rita leads Valentine back to Kern’s house. He says she should keep the dog after confirming that he sent the money for the expenses. She returns the extra amount to Kern after meeting the vet’s expenses. Valentine hears that Kern is eavesdropping on a male neighbour’s sexual telephone conversation with his male lover. She tries to convey to him her concerns about respecting the privacy of his neighbour. The judge challenges Valentine to reveal the eavesdropping to the neighbour. She goes to do so but is horrified to see the man’s young daughter on the telephone extension, listening to the same conversation. Upon her return, Kern tells her that their actions of telling or not telling, and spying or not spying make no difference to the eventual outcome of other people’s lives. As the conversation goes on, Valentine tells that her brother was fathered by someone else other than her biological father. Before leaving, Valentine also hears a conversation between Auguste and his girlfriend, Karin (Frederique Feder), neither of whom she has met. Auguste passes his exam to become a judge and credits his success to the dropped textbook.
That evening, Kern writes a series of letters to his neighbours and the court confessing his spying activities, and the community files a class action. Later, at the law courts, Kern sees Karin flirting with another man. When Valentine confronts Kern, he says it was her feeling of disgust that prompted him to confess. They discuss the nature of altruism and Valentine asks if he has ever loved or been loved. Kern evades the question and instead recounts a case in which he mistakenly acquitted a sailor, only to see him live a life free of crime.
Auguste has been unable to reach Karin by telephone since his graduation so he drives to her flat and climbs up the building. Through the window, he sees her having sex with another man and leaves, distraught. He takes his grief out on his dog and at one stage abandons him at a lamppost. On Karin’s personalised weather information service she is predicting that the weather around the UK will be perfect. She is happy about this as she is about to sail there herself soon (with her new boyfriend who owns a yacht).
The day before Valentine leaves for England, she invites Kern to her fashion show. Stormy weather is gathering and Kern seems to sense that Valentine will soon be in danger from it. After the show their conversation turns again to Kern’s doomed love life. His answer betrays echoes of Auguste’s recent life, including the infidelity and the dropped textbook. He says that the girl he loved died in an accident after he followed her across the English Channel. He also says that his last case as a judge pitted him against his ex-girlfriend’s lover. By co-incidence, Auguste’s first case as a judge is Kern’s trial. Kern tells Valentine in more detail about a dream he had about her. In the dream, she is 50 years old and happy and with a man she loves. As they say goodbye, Kern and Valentine plan to meet again in three weeks’ time when Kern will give her one of Rita’s puppies.
Finally, Valentine boards the ferry to England. We also see Auguste on the ferry, reunited with his dog. Kern is choosing the puppy he will give to Valentine on her return when he hears disastrous news; the storm has hit the English Channel and both the ferry and the yacht have sunk. Kern fears the worst, only seven survivors are pulled from the ferry. We see six of them in freeze-frame: Julie and Olivier from Blue, Karol and Dominique from White, Auguste (without his dog) and finally Valentine. Auguste and Valentine are looking into each other’s eyes, inviting the viewer to believe this is the man from Kern’s dream, with whom she will find happiness. The final image replicates the iconic ad poster of Valentine, but this time with real emotion showing on her face.