A car in which five years ago a teacher was murdered is returned to the victim's husband. Pullman re-opens the unsolved case, hoping her team can track down the dead woman's secret lover, and a clue soon leads them to a male prostitute. Pullman had worked on the original case and been troubled throughout by the lack of emotion shown by Nancy's husband Stephen

The murky death of Joe Walsh, General Secretary of the Crane Driver's Union, whose body was found in the Thames in 1975, is reinvestigated. At the time of his death, Walsh stood accused of stealing money from the union's account. The team find themselves at the centre of a political minefield, with suggestions of misappropriated union funds, MI5 involvement and a union leader whose threats of strike action were gravely threatening the national interest.

When a serial dog killer starts stalking local parks, the team are reluctantly forced into taking on the case.

The vicious criminal Chopper Hadley, who has been back in the country for a week, is searched for by the team. However, Halford is viciously intimidated and the squad start to realise the full danger of their target. Desperate measures are used and Brian is sent undercover to get Hadley once and for all.

Ray Cook, a legendary criminal has turned prime time celebrity. The team set off to find him, because there was a notorious bank job which left a cashier dead. He is a suspect, but was he responsible, or is he as innocent as he claims?

The team are on the case of the ice cream bandit, an armed robber who's targets were the ice cream vans of two feuding ice cream manufacturers in the mid 1990s. The battle between the two families erupts into violence, so UCOS decide to track down the bandit and stop the conflict once and for all.

Pullman struggles to keep the boys in line as their chequered pasts begin to be revealed. Halford is determined to nail a vicious criminal who has so far eluded him and in doing so he puts himself in grave danger. Standing receives a surprise visitor which shocks him. Pullman is increasingly frustrated and weighs up an opportunity that could end her time in UCOS.