Garth goes undercover as a security consultant to track down Eva Richardson, the mind behind a powerful vice ring. He uncovers a link with the drug squad and, after one of Eva's girls is discovered dead in suspicious circumstances, an internal investigation is launched with results in Liam being posted back to investigate his old drug squad colleagues. In an attempt to infiltrate the web of corruption, Garth sets up a drugs deal. But when this goes disastrously wrong, it becomes clear that someone of high rank is playing for the opposition.

The second part of a drama in which Liam and Garth investigate fellow officers suspected of collusion with a powerful vice ring. Liam's allegiances are put to the test when it becomes apparent that his old friend, senior officer Craig Griffin, is also in on the deal. Garth must race against time to find a key witness held captive by two corrupt policemen.

Liam and Garth try to crack a paedophile ring which is operating through a sophisticated website. Liam befriends the wife of the webmaster and Garth goes undercover in prison to make contact with two of the principal players. After winning their confidence, he discovers that a grisly crime is about to be committed.

Liam infiltrates a white supremacist group which has begun a systematic petrol tanker bombing campaign. Garth is assigned to provide backup and support to Liam's family, but when a vengeful man - whose imprisonment Garth was responsible for - tracks him down, he finds instead that his presence is putting them in mortal danger.

Liam discovers that the leader of the white supremacist group is not who he seems. An unwelcome visitor from Garth's past mistakes Liam's family for Garth's - and sets out to exact his revenge on the man whose evidence put him in prison.

Liam and Garth pose as drug dealers in a bid to capture Jamie Lamb, the country's biggest cocaine importer. They infiltrate his trusted entourage and fit in so well that when Lambs wife leaves him taking his two daughters with her, he asks Liam and Garth to kill her and bring back proof in exchange for a shipment of cocaine.

The second part of the story in which Liam and Garth infiltrate drug baron Jamie Lamb's gang. Kelly persuades Tania Lamb to help them fake her murder. Only when the ""proof"" is taken back to Jamie, he turns nasty and ups the stakes, declaring that the deal is not complete until his daughters have been returned to him. Liam and Garth have are forced to use Lamb's daughters as insurance to make sure the exchange of drugs takes place. In a fit of guilt, Tania calls Jamie and unwittingly exposes Garth and Liam's set-up leaving them cornered with no back up.

Police Chief DI Holland challenges gangster Charlie Pearce in order to regain control of a tough area of the city, but is shot dead on his way back from a public meeting with the area's residents. Pearce is, of course, the chief suspect. Liam, Garth and Kelly set themselves up as an operation selling expensive fake watches and it's not long before Pearce and his heavies call round for their first 'insurance' payment. Liam is embraced into Charlie Pearce's fold when, through a stroke of good fortune, he saves Pearce's life. Unfortunately Garth's unresolved issues with his brother Chris land him in deep trouble when Chris tracks him down and blows his cover. Liam's nerve is tested to the limit as he faces the choice of killing his partner Garth to prove his allegiance to Pearce, or coming clean and risking being killed himself.

Gangster Charlie Pearce invites Liam to get involved with a lucrative gun shipment for Jeff Mohandas. The deal becomes further complicated by Pearce's daughter-in-law, Kim, who is having an affair with Mohandas and has hatched a plot to kill both her husband David and Charlie Pearce. Liam, once again, finds himself out of his depth and without backup as a series of double-crosses turn a simple deal into a bloodbath.

A group of anarchists kidnap the grandchildren of millionaire media mogul Clayton Waddington, but the family is adamant that the police should not be involved, thus avoiding a public scandal for their business. Liam and Garth are brought in under the guise of insurance company ransom negotiators and Kelly goes undercover living on the streets in an attempt to trace a homeless girl who has been linked to the scene of the abduction. Waddington agrees to the ransom demand, but tries to get the upper hand on the criminals by marking the cash. Garth is sent to deliver the money, but the kidnappers are smarter than anyone has realised and he finds his safety is severely compromised.

Part two: Liam and Garth assume the guise of insurance company ransom negotiators when a millionaire media tycoon's grandchildren are kidnapped. Garth befriends Waddington's granddaughter and tries to save her, only to find that she has a quite different agenda.

A woman is found murdered in her flat in almost identical circumstances to one six months earlier. The victims have one thing in common – they are both members of the same Internet dating site. Kelly goes undercover and builds up a relationship online with prime suspect Dark Angel, but her tactics come close to entrapment. Liam's colourful love life threatens to compromise the operation when a spurned girlfriend starts to stalk him.

Part two of an investigation into a series of murders of members of an Internet dating agency. Garth falls back on a part he has played before – that of a sex offender – in an attempt to get close to Grendle, but his attempts to lure Grendle into revealing his secrets backfire spectacularly. Exasperated by Liam's womanising, his estranged wife, Pam, joins the very same Internet dating agency unwittingly sets herself up as a potential victim. The series reaches a terrifying climax as it transpires that the real killer is much closer than anyone realises.

Liam and Garth go undercover to gain the trust of an arrogant armed robber. But as they are sucked into his brutal world, it becomes unclear who is manipulating whom.

Liam and Garth struggling to keep their cool on an undercover operation against armed robber Sean Denning as the court hearing approaches.

A group of soldiers, trained to go undercover in Northern Ireland, feel they have been treated unfairly by the MOD and threaten to start their own bombing campaign.

Liam and Garth continue their infiltration of a group of former soldiers threatening to terrorise the UK. The Houses of Parliament are the target and Liam and Garth must travel with the bomb rather than reveal their identities.

A drugs baron on remand in a Category A prison is still conducting his business with the outside world. When one of the witnesses in his case is found murdered, leaving only one remaining and in terrible danger, Garth goes undercover as a prison warder to observe him.

Liam and Garth's undercover mission continues, as it becomes apparent that one of the prison guards is working for drugs baron, Hunter.

Liam and Garth pose as security consultants in order to protect a controversial gay Home Office minister who has received death threats over his plans to legalise cannabis. Meanwhile, Liam's daughter's boyfriend offers information to drug dealers about Liam and Garth's operation in order to pay off his drug debts.

The threat to government minister, Jertemy Church's life becomes more real, with a controversial speech on drug laws looming. As Liam and Garth find themselves under mounting pressure to protect him, those closest to Jeremy Church appear to have scores of their own to settle.