I enjoyed the hell out of this film, easily the best of the five or so films I have watched since this CC list begun.  How much I enjoyed this film was a bit of a surprise for me, perhaps I am ageist but I just didn't think a film this old would have this much of a punch in the suspense and horror departments. Clouzot's 'Diabolique' is well-crafted murder mystery (so mysterious it is not about who did it but how) that is as admirable from a technical standpoint as it is rewarding as suspense/horror fare.  The dvd case mentions that this was influential in Hitchcock making 'Psycho' and one can instantly see the same loving appreciation for pure cinema and archtechtonic control of mis-en-scene.  The bulk of the story is situated in and around a boarding school in France and I love the way the environment is used to give the impression of a dimensional plane where the drama unfolds... windows overlook other key scene sites, and you feel properly situated in the space.  This seems like a minor thing to bring up but I have a real fondness for this sort of ... well archtechtonic control of mis-en-scene (I  don't know how else to say it).  Kurosawa is a master of creating space, and Clouzot is working nearly on this level.  I know Hitchcock gets a lot of praise for his pure cinema but I find something lacking more often then not in his films... the big exception being Psycho... which does have the spectre of Diabolique.