Paris, France, 1942, during the Nazi occupation. Robert Klein, a successful art dealer who benefits from the misfortunes of those who are ruthlessly persecuted, discovers by chance that there is another Robert Klein, apparently a Jewish man; someone with whom he could be mistakenly identified, something dangerous in such harsh times.
During an orgy, Some old and wealthy notables are being murdered by a small group of leftist young revolutionaries. Very soon the police are tracking down Virgile Cabral, the leader of the group. Meanwhile, Virgile's brother and only relative, Vincent, a violinist (and a thief), comes back to Paris. They have not seen each other for three years. Vincent does not believe in the revolution. He only tries to live as he wishes to live. But by looking for his hunted down brother, he has no other choice than to be involved in a fight that is not his.
Matou is an innocuous, gentle-looking man. He is married to a formidable, even a frightening woman, who is as dissatisfied with him as he is with her. He knows everything there is to know about restoring and authenticating manuscripts, particularly ancient ones, through his job at the museum. One day, it occurs to him that his skills could be put to use in a more personal way, and he embarks on a private career of re-arranging the documents of people who have had the misfortune to be married to the wrong people.
