Following the deaths of Georgia and the witness it is Steve who gets a grilling as to the police presence at the hospital whilst Lindsay is accused of attacking her neighbour, which she denies. Steve discovers that a nurse on the witness's ward, Claire Tindall, was threatened into giving the killer access by a man she knows as Joe, but whom she is unable to identify. Lindsay continues to search for vanished teenager Carly Kirk and Kate is drafted in as her assistant - in reality a move to try and get Lindsay to admit her guilt - but Lindsay sees through the ruse. After Kate's cover is blown Lindsay is questioned again and claims that she rang the hospital to ask that the witness exonerate her but she is disbelieved and Hastings arrests her for conspiracy. At her interview she points out that Steve visited Claire unofficially and Hastings has financial problems and a broken marriage that could make him just as culpable but she is nonetheless held in custody. Meanwhile DCC Dryden finds himself in the frame for a driving offence supposedly committed by his wife.

Lindsay wakes up in a lock-up and is questioned by her abductors. Prasad soon kills his accomplice, Cole, but Lindsay outwits him and makes him admit on the phone that he and Cole were working for Dryden, who set up the ambush. Steve locates her at her dead mother's bedside and she is granted bail, unaware that Prasad, whom she believed that she killed in self-defense, is still alive and demanding immunity. Cottan brings in his old mate Morton for some dirt on Dryden and it is revealed that Dryden had sex with Carly Kirk. He is arrested and questioned, admitting that he had a brief affair with Lindsay, who became vindictive when he ended it. Steve also finds out that Lindsay has had an abortion.

When a criminal is shot dead by a police armed-response unit led by Sergeant Danny Waldron, AC-12 gather evidence suggesting it was a deliberate killing rather than self-defense.

DS Steve Arnott believes there is a dark secret in Danny Waldron's past. Then the spotlight falls on his questionable conduct in a previous inquiry - the Lindsay Denton case.

A dismembered body is discovered, and worries grow when Roz fails to report for duty. After further questioning of Michael Farmer unearths crucial new information, AC-12 challenge the case against him.

As shocking new evidence is unearthed, AC-12 step up their investigation into the case against Michael Farmer.

The discovery of new forensic anomalies appears to provide AC-12 with a major breakthrough. Meanwhile, Nick Huntley comes under scrutiny.

When three police officers are shot dead during the hijack of a seized drugs transport, AC-12 move in to investigate possible police collusion.

As the hunt for H intensifies, Steve and Kate wonder if Hastings is guarding a dark secret.

AC-12 investigate DCI Jo Davidson's apparent mishandling of the murder of an investigative journalist.