Jack Carter's Law is a 1974 British crime novel written by Ted Lewis

Ted Lewis (writer)

Ted Lewis was a British writer.He was born in Manchester, an only child. After World War II the family moved to Barton-on-Humber...

. It is a prequel

Prequel

A prequel is a work that supplements a previously completed one, and has an earlier time setting.The widely recognized term was a 20th-century neologism, and a portmanteau from pre- and sequel...

 to Lewis' best known work, Jack's Return Home

Jack's Return Home

Jack's Return Home is a 1970 novel by British writer Ted Lewis. An uncompromising novel of a brutal half-world of pool halls, massage parlours and teenage pornography, it was memorably brought to life in the cult film Get Carter, starring Michael Caine as Jack Carter...

which was adapted into the film Get Carter

Get Carter

Get Carter is a 1971 British crime film directed by Mike Hodges and starring Michael Caine as Jack Carter, a gangster who sets out to avenge the death of his brother in a series of unrelenting and brutal killings played out against the grim background of derelict urban housing in the city of...

in 1971. On Christmas Eve

Christmas Eve

Christmas Eve refers to the evening or entire day preceding Christmas Day, a widely celebrated festival commemorating the birth of Jesus of Nazareth that takes place on December 25...

, Jack Carter learns that a supergrass

Supergrass (informer)

Supergrass is a slang term for an informer, which originated in London. Informers had been referred to as "grasses" since the late-1930s, and the "super" prefix was coined by journalists in the early 1970s to describe those informers from the city's underworld who testified against former...

is about to inform to the police and put him and his associates away for lengthy prison sentences. Carter attempts to hunt down the informer, but it proves a far more dangerous task than he anticipates.