Don't worry, I won't give the ending away (Les Diaboliques)

Clouzot's "Les Diaboliques" (mistranslated as "The Devils") is a bit creaky at times but overall an entertaining and captivating suspense film that gives a great look at the poverty and desperation on post- WWII Europe (France, in this case); set in a boarding school in a Paris suburb, run by a horrible tyrant and misogynist, who's terrible to his wife, flaunts in her face the fact that he has a mistress (Simone Signoret) whom he's nasty to as well, mean to the students, a brutal bully to his staff. The two women plan to kill him, and though we rarely root for the killers in a movie in this case we do - we can't wait for them to off him. But things don't go the way the expect. At the end of the movie, a hilarious title screen tells us: Don't be devilish; do not give away to your friends what you have just seen. So I won't, but the ending is a quite a surprise, even if it strains credulity. The movie is or ought to be well known for its several very powerful scenes: the dining room in the boarding school when the schoolmaster, Delaselle, commands his wife to swallow a mouthful of fish; the two women drowning Delasselle in a bathtub while the tenants upstairs try to listen to a radio quiz show, and most of all the final sequence, as Madame Delasselle stumbles through the hallways of the boarding school pursued by a phantom. A clever movie whose techniques of editing (the man appearing from behind the door in the otherwise empty hotel room) have been used successfully by many suspense directors over the past 50 years.