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.