Garth has been released following Dominic's murder and is furious with Liam for failing to back him up. Nicola tries to help her boyfriend with his debt to drug dealers.

With the government intending to legalize cannabis, the controversial policy has made Jeremy Church a target, and Liam and Garth are sent to prevent an assassination.

Garth realizes one of DCI Davies's team is working with Hunter and forms a strategy to identify the culprit before they get to undercover cop Debbie, a key witness.

Liam and Garth are sent undercover to a maximum-security prison as the case against villain Vincent Hunter looks set to collapse.

The base of the group Liam and Garth are infiltrating has been attacked by ex-IRA men pursuing vengeance. The shoot-out tips Garth over the edge, and Liam must find him.

Liam and Garth are called in by the Ministry of Defense to infiltrate a group of disgruntled former undercover soldiers planning a campaign of terror.

As Liam and Garth continue to try to gather new evidence against Denning, their task is complicated by a malcontent ex-policeman working with the defense team.

Liam returns to duty after the shooting and helps capture crazed armed robber Sean Denning. But when Denning gets out on bail, Liam and Garth must go back undercover.