La Part du Feu is a French idiom, and has to do with making a sacrifice for some gain. Hansen (Michel Piccoli) is a wheeler-dealer and building developer, who apparently manipulates people and situations just for the joy of it. In this melodrama, it was his wife Catherine's (Claudia Cardinale) money which enabled him to get into the real-estate business, but these days she is somewhat neglected. Jacques (Jacques Perrin) is his assistant, an eager but none too confident young man who has been having an affair with Catherine. The two of them worry a great deal about Hanson discovering their relationship.
Source : allmovie.com