Line of Duty season 3
Steve Arnot – is a detective who transferred to the department for the fight against corruption after a failed anti-terrorist operation with a random victim. Kate Fleming (another detective) was appointed to lead the investigation of a single case in which the suspect popular and successful colleague, Chief Inspector Tony Gates. Although Gates cleverly manipulates the figures of his department, Steve Arnot doubts whether he was involved in a crime or Gates just make a scapegoat.
A hardened criminal is shot dead by an armed-response unit led by Sgt Danny Waldron, who claims they were acting in self-defence. But when AC-12 gather evidence suggesting it was a deliberate killing, DC Kate Fleming is sent undercover into Danny's team to find out more. She is quick to identify tensions within the team - only for her own conduct to come under scrutiny.
The shooting at the drugs house intensifies the scrutiny on Danny Waldron's armed-response unit, who once again close ranks. But with Kate Fleming on the inside, AC-12 feed in new information that helps her expose cracks in the team's story, while Steve Arnott looks deeper into the suspect sergeant's background and makes a shocking discovery. However, the anti-corruption cop's life is complicated by an investigation into his own past conduct.
DS Steve Arnott believes there is a dark secret in Danny Waldron's past. But while DI Cottan is commended for cracking the Waldron case, the spotlight falls on Arnott's questionable conduct in a previous enquiry.
Fresh testimony launches AC-12 back on the trail of the Caddy, a corrupt officer with links to organized crime. But new disturbing evidence suggests the Caddy may reside within AC-12.
AC-12's loyalties are divided when DS Steve Arnott comes under scrutiny from his colleagues. With his career in jeopardy, Arnott turns to an unlikely source for help.
DS Steve Arnott is arrested on suspicion of murder but continues to protest his innocence. Does DC Kate Fleming's undercover operation hold the key to Steve's guilt and the identity of the Caddy?