Available on Blu-ray now.

In a seedy, French provincial boys’ boarding school the headmaster Delassalle (Paul Meurisse) is a nasty piece of goods. He abuses his wife Christina (Véra Clouzot) and his mistress, Nicole (Simone Signoret), who are both teachers at the school where the stygian atmosphere is just as fetid as the clogged swimming pool in the grounds. Unforgivably Delassalle’s mean with the staff’s wine ration. It’s all very French.

Madame Delassalle and Nicole bond and hatch a plan to dispatch the horrible husband. The murder is depicted in all its banality that even the velvety shadows of cinematographer Armand Thirard can’t hide. In the superbly clean, meticulous Blu-ray transfer the images have a special lustre.

It’s easy to kill someone, but disposing of the body is harder. Nicole and Madame D have that all worked out too. But can they pull it off and fox the intrusive no-win-no-fee private detective (Charles Vanel) who is hanging about the school gates like a bad smell?

Clouzot keeps the twists and turns of the sulphurous story snappy and Signoret is a great blend of scheming and sultry. What film buffs will appreciate most about Diabolique is the fact that it was a huge influence on horror filmmakers to come. That old klepto Alfred Hitchcock used it as a template for his pioneering Psycho, made five years later – copying everything from the flushing toilet to a scene where Christina falls back against, and slips down, the surface of a wall (just like Marion does in the shower).

Robert Aldrich’s Hush… Hush Sweet Charlotte, Polanski’s Repulsion and any number of William Castle “creak and shriek” shockers all owe Clouzot a debt of gratitude. But the original Diabolique is a classic of its kind, right down to the startling twist at the end.