This is adapted by Claude Chabrol from a script by Henri-Georges Clouzot which he began to direct himself as Inferno in 1964, but abandoned due to illness. So yes, it's a collaboration between both the French Hitchcocks! But this isn't exactly what that suggests; a twisty suspense thriller leading to an astonishing climactic bombshell...
It starts out like it’s going to be a psychological drama with François Cluzet as a bourgeois hotelier married to a sexy/beautiful younger woman who is charmingly flirtatious. And they have an adorable son. The wife is played by Emmanuelle Béart and it's not difficult to empathise with how insecure she makes him feel! All that sexual tension...
The cast gathers in an upmarket hotel full of tourists, but this doesn't turn into an Agatha Christie murder mystery; the uncharismatic manager becomes increasingly jealous. His possessiveness develops into psychosis until he ultimately presents as a violent threat to his family. We do get a big payoff, but it's harrowingly plausible.
And the slow build to the shocking climax is well worth the wait. There are no jump scares or gimmicks, just the hallucinogenic perspective of a sick man becoming a psychopath. Back then, Béart was an arthouse pinup and Chabrol gives us some glamour; but she's also a fine woman in peril. And hell, maybe she isn't so innocent...