This is part of the cinema's Classic Films season. Full details here.
Chicago Reader review:
The notoriously ruthless 1955 thriller by France's most neurotic director, Henri-Georges Clouzot (The Wages of Fear). Clouzot cast his own wife, Vera, as an invalid who plots the murder of her husband, assisted by his mistress (Simone Signoret). Set in the rotting confines of a private school for boys, the film is cruel, sour, and—unfortunately—very effective.
Here (and above) is the trailer.