Jean Renoir, 1939. A French country-house weekend before the war. Sight & Sound top-10 fixture for decades.
From Wikipedia
The Rules of the Game is a 1939 French satirical comedy-drama film directed by Jean Renoir. The ensemble cast includes Nora Gregor, Paulette Dubost, Mila Parély, Marcel Dalio, Julien Carette, Roland Toutain, Gaston Modot, Pierre Magnier and Renoir.