Claude Chabrol's La Rupture | The Breach (1970)

Hélène Régnier (Stéphane Audran) is the wife of the psychopathic Charles (Jean-Claude Drouot), who violently begins the film by throwing their child down, who hits his head. In self defence Hélène batters him with a frying pan and rushes from the house, upon which neighbours come to her aid and she is driven to the hospital. Charles has no job and Hélène has run the family on the paltry sum she earns from her barmaid job, has kept the family afloat, although Charles's father is a wealthy businessman, but will do everything he can to protect his son and besmirch the reputation of his daughter-in-law, whom he sees as unfit for Charles: yes, it's of course Chabrol taking a poke at the moneyed hypocritical upper middle class.

Temporarily Hélène finds cheap accommodation at a boarding house opposite the hospital, run by Madame Pinelli (Annie Cordy) and (to a much lesser extent) the alcoholic Monsieur Pinelli (Jean Carmet), and the house more than a little resembles La Maison Vauquier of Balzac's Le Père Goriot. And here to stay on a temporary basis is slimeball Paul Thomas (Jean-Pierre Cassel), in theory staying there because of an illness, in reality there to paint Hélène black. He tries to do this by getting Pinelli into a drunken stupor while his wife is away, drugging the Pinellis' daughter and showing her porn videos by Thomas's girlfriend posing as Hélène, and finally (desperately) spiking Hélène's morning orange juice with LSD.

Needless to say, perhaps, Thomas's plan doesn't work: Hélène has already informed him that she knows he's a plant designed by Régnier père to make her look bad as he wants custody of the child, but anyway Thomas loses what little cool he had by killing Régnier's son Charles.