Line of Duty

After a criminal is shot dead during a police raid, AC-12 begins gathering evidence against Sergeant Danny Waldron, but it may be hard to get any information out of Danny’s tight-knit unit.

Fleming uses her undercover role to increase the pressure on Waldron's armed response unit. Meanwhile an old AC-12 investigation comes under legal scrutiny.

As the evidence mounts against them, Danny’s squad members close ranks. Then DS Arnott makes a shocking discovery that could change the focus of AC-12’s inquiries.

Arnott believes Waldron compiled a list of his childhood abusers. But while DI Cottan is commended for cracking the Waldron case, the spotlight falls on Arnott's questionable conduct in a previous enquiry.

Lindsay Denton sets out to clear her name, while Arnott and Hastings interrogate Bains on suspicion of murder.

AC-12's loyalties are divided when Arnott is suspended from duty. With his career in jeopardy, Arnott turns to an unlikely source for help.

Arnott is arrested on suspicion of murder but continues to protest his innocence. Does Fleming's undercover operation hold the key to Steve's guilt and the identity of the Caddy?