Nicola's drug-dealing boyfriend offers to expose Liam and Garth; Liam gets romantically involved with the hotel owner.
Liam and Garth help protect a controversial government minister.
Liam tries to convince the drug baron that escape is the only option.
Garth and Liam go undercover as a prison guard and prisoner o figure out how a criminal empire is being run from behind bars.
The group splits into pro- and anti-violence factions; the explosion at the pub leaves Garth shaken.
A group of former soldiers threaten terrorist attacks unless their financial demands are met.
The undercover operation against Sean Denning escalates as a court hearing approaches.
Liam and Garth go under cover to gain the trust of an arrogant armed robber.
Garth and Kelly sign on to an Internet dating site to catch a serial killer.
Kelly registers as a decoy to find a killer who finds his victims though a dating service Web site.
Garth and Liam masquerade as insurance company ransom negotiators after the grandchildren of a wealthy media magnate are kidnapped.
Liam and Garth negotiate with the kidnappers of a media mogul's grandchildren.
A seemingly straightforward arms deal goes awry for Liam as he attempts to entrap gangster, Charlie Peace, after the murder of a police chief.
Police Chief DI Holland challenges gangster Charlie Pearce in order to regain control of a tough area of the city.
The police fake Tania's death; Garth has trouble dealing with his father's death.
Garth and Liam force a drug lord's mistress to turn against him.
Undercover cops pose as drug dealers in an attempt to catch Jamie Lamb, one of the biggest importers of cocaine into the UK.
When an Internet dating site becomes a serial killer's hunting ground, Garth and Kelly pose as potential victims.
Liam is profoundly affected by the death of Dave Street; Chapman can't be arrested; Chapman's true identity is revealed.
Liam infiltrates a white supremacist group; Garth is tracked by a vengeful man.
Garth and Liam know the identity of the mastermind behind the ring, but the problem is getting hard evidence.
Undercover cops try to crack a paedophile ring operating through a sophisticated website.
While Liam tries to gain the confidence of senior officer Griffin, Garth must race against time to find a key witness held captive by two corrupt policemen.
A couple of undercover cops investigate fellow officers suspected of collusion with a powerful vice ring.
Operating undercover in prison, one half of the duo makes contact with two of the principal players and comes to realize that a terrible crime is about to happen.
Liam tries to infiltrate a white supremacist group which is bombing petrol tankers.