A terminally ill cancer patient is found murdered in hospital. Bennett and Allen are sent to investigate a violent rape, but the victim knows more than she's prepared to admit.

An investigation into pornographic images found on Ludlow's daughter's computer leads to a murder scene. Hannaford starts to feel the pressure and Drinkall refuses to take a back seat, despite having been suspended from duty.

Hannaford raises concerns about Drinkall's health. Bennett and Allen are puzzled as to why someone should be collecting the mail and bringing fresh flowers to a man dead for two months. Drinkall follows up a tip-off about a planned robbery on a pub. Brazil takes matters into his own hands after a suspect gives him the run-around, but gets more than expected in return.

The body of a 14-year-old girl is discovered in a derelict building. The team soon discover she was engaged in underage prostitution, and local boxer Vinnie Harper is implicated. Allen fights for his career following his breakup with Lucy.

Drug dealer Tommy Defty has a reputation of being untouchable. He uses children as drug runners, as they're under the age of criminal responsibility. Llewyn decides to play Defty at his own game by using his mother as leverage.

Down and out Nikki is the latest member of the community poisoned by a stranger offering a drink. The situation takes a dark turn when vagrant Jackson Hanley dies. Hannaford attempts to prove Gibbs is dealing in stolen goods.

A woman is found dead in a bus shelter outside her own home, but the neighbours are reluctant to get involved. Drinkall's disappearance leads his colleagues to reopen an old case, after it becomes apparent that Drinkall runs his own inquiry. A shopkeeper at the end of his tether resorts to drastic measures in order to be taken seriously. Ludlow's personal life becomes the talk of the department after Brazil reveals Ludlow's secret.

Relations are strained between Ludlow and Brazil after Ludlow discovers who spilled the beans on his affair. They find themselves in further trouble when the suspect they've just arrested collapses of a heart attack. Members of a hostile and divided community seem intent on blaming each other when a prominent human rights lawyer is shot and her body moved from the scene of the crime. Drinkall tries to strike a deal with his informant in order to find out who supplied the gun. Dissatisfied with results, he goes it alone and goes undercover on his own private mission – with devastating results.