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.

Alain Delonas Mr. Robert Klein
Jeanne Moreauas Florence
Francine Bergéas Nicole
Juliet Bertoas Jeanine, Robert's mistress
Jean Bouiseas Seller of the painting
Suzanne Flonas Concierge of rue des Abbesses
Massimo Girottias Charles, Florence's husband
Michael Lonsdaleas Pierre
Michel Aumontas Jew Affairs Section Official
Roland Bertinas Newspaper Director
Gerry Fisher