Plender

Brian Plender is a glittering evil on par with Patricia Highsmith's Tom Ripley or Jim Thompson's Lou Ford. In Plender the author of Get Carter and GBH delivered a tense and psychologically complex tale of revenge and blackmail that rightfully belongs among crime fictions most chilling ranks. Two men share a common history. Growing up together in the small town of Barton-Upon-Humber in Lincolnshire, England, Peter Knott is everything that Brian Plender wishes he were.
Knott is suave, good-looking, an exemplary student and popular. The friendship they maintain is as important to Plender as it is forgettable to Knott, and this eventually leads to a lasting humiliation for Brian. Years later Brian Plender is a dangerous man. A private investigator who specializes in extortion, blackmail, and intimidation, Plender is a manipulative psychopath capable of anything. Knott meanwhile is a man adrift.
He is beholden to his wife for money, which he makes taking photographing catalogs for her father's large mail order company. His wandering eye, array of fetishes, and a taste for younger women, has led Knott through a series of sordid affairs. The two haven't met in years so Brian is therefore quite surprised to spot Peter at a seedy bar with a girl too young to be his wife and he decides to follow the pair.
Plender relives the humiliations of his youth just as Knott finds himself on the wrong side of the law in the most horrific way imaginable. Starting out as a long-lost friend and slowly, carefully, revealing himself to be anything but that, Brian Plender is a brilliantly macabre invention that readers won't soon forget.