An essential film in Chabrol’s vast oeuvre, La rupture is an “elegant, imperiously assured study in sex, mendacity and murder in the French middle class” (Terrence Rafferty). The breach of the title refers in part to the eruption of violence in the seeming domestic quietude of the Régnier household when a woman’s unstable husband attacks her and their son, sparking a custody battle of an unusually appalling nature. The Paramount’s Claude Chabrol program supplements and screens along with the Chabrol retrospective taking place at the Harvard Film Archive March 11-27.