The main character attempts to seduce wife and his mistress (his next-door neighbor's wife) into a menage-a-trois, which backfires when the two women fall for each other and leave together at the end.
This novel is difficult reading, with obtuse wording and a plot that can only be understood by closely examining it. Really, there is no horror in this novel. It is recommended for people looking for satire rather than horror.
This novel has also been released as a British television adaptation.