The Knock is a British television drama series, created by Anita Bronson and broadcast on ITV from 1994 to 2000, which portrayed the activities of customs officers from Her Majesty's Customs and Excise. The series derived its name from the distinctive 'knock knock knock' command used over the radio to synchronise a raid.

Writer Mark Easterbrook has a vested interest in solving the murder of a priest. That's because Mark himself is under suspicion. But to save his reputation and put the real killer behind bars, he'll have to go through a mysterious list of names that's suddenly turned up and may hold the key to the murderer's identity.