Detective Sergeant Daniel Miller is suspended from the London Metropolitan Police so that he can be secretly deployed to a small English town on an undercover assignment to uncover Britain's major suppliers of heroin and crack cocaine. He poses as a heroin addict and manipulates an unsuspecting junkie into working with him so that he can infiltrate the local drug network and work his way up the supply chain. The line between duty and criminality begins to blur as Miller's investigation becomes increasingly dangerous the closer he gets to finding the source of a drug trafficker.