Diabolique twists the convention of a love triangle into something completely different. It might more accurately be described as a hate triangle. Paul Meurisse’s character can’t stand either his wife, Vera Clouzot, nor his mistress, Simone Signoret. And they, in turn, hate him, and, somewhat more naturally, don’t like each other very much.
Having resolved to kill the haughty husband/lover, Clouzot and Signoret bungle the act, or so it seems. They become panicky when an increasingly disturbing series of incidents both seem to point out their guilt and leave doubt that Meurisse is actually dead. The tension between them increases as a result, as Clouzot’s innocent/hypochondriac character seems to physically melt down, whereas Signoret, steely and determined, only becomes more intense.
Essentially, all three characters are unsympathetic. Both husband and mistress are inflexible and domineering, while the wife passive/aggressively wants the other two to feel guilty merely for existing. Admittedly, she is wronged by both the others, and is the only one of the three who seems at home working with the kids they’re all responsible for.
Clouzot’s collapse literally in the face of her ‘victim’ is thoroughly convincing, and builds at a dizzying pace to its macabre climax. Having said that, and, as much as I admire Diabolique as a whole, I admit there are a few questionable turns.
It seems odd that the two ‘murderesses’ can’t find a more discrete place to dump the body than the pool on the same school property where they all work. The ‘murder’ sequence itself is fairly convincing from Clouzot’s point of view, which helps suspend the audience’s disbelief, but Meurisse could’ve survived the Inquisition’s test for witchcraft.
What elevates this movie’s status as one of the best thrillers, despite a few little flaws, is the creepiness lurking in everyday, even dull circumstances, which each of the main characters allows to grow, with truly ‘diabolic’ consequences. 10/10.