The protagonist of Red, Valentine, a student making money on the side as a model, almost kills a dog by running over it with a car. Soon she meets the dog’s owner, a bitter man living nearby – a retired judge. The accident allows Valentine to discover the peculiar way in which the judge spends his free time. He has a hobby, which is not very ethical: he uses a specially equipped radio receiver to eavesdrop on his neighbours' conversations, finding pleasure in entering other people's intimate lives. During one of her visits, the girl realises that she is also being eavesdropped upon. The judge knows her conversations with her boyfriend who works abroad and also knows her family’s problems concerning her drug-addict brother.
The girl's attitude towards the judge becomes ambivalent; she is close to both contempt and a strange fascination, wanting to find out the reasons for his behaviour. Her phone calls with her boyfriend, previously filled with intimacy, now become frigid. Valentine is aware that they are being overheard. Insincerity sneaks into their relationship, heralding their inevitable parting. This seems to benefit the judge, who seems to have some mysterious plans for his new female friend's emotional life.
Just as the cynicism of the ageing man seems intriguing to Valentine, he is fascinated by her kindness, righteousness and gentleness, which go hand-in-hand with her subtle beauty. Under the influence of Valentine – and for her sake – the bitter man changes his behaviour and reveals his vile deeds to his victims and the police, ready to suffer the consequences. Moreover, he opens up to the girl, revealing to her the truth about past events that resulted in his insensitivity to others. Betrayed in his youth by the woman he loved, he exacted revenge on his rival after years by using his position as a judge. His revenge satisfied him, but it also forced him to live on with the awareness of his pettiness. All these events make up a life lost, deprived of love, friendship, closeness to another person...