The wife and mistress of a cruel school master collaborate in a carefully planned and executed scheme to murder him. The plan goes well until the body, which has been strategically dumped, disappears. The psychological strain starts to weigh on the two women when a retired police investigator begins looking into the man's disappearance on a whim.
The husband is still a brute, and the swimming pool is still moldy, but the new Diabolique fails to translate into anything more than the latest ham-handed Hollywood makeover of a European classic.