Line Of Duty is back tonight on BBC One for its final episode of the current series.
The hit police corruption drama returned for a fourth run earlier this month on its new home on BBC One.
When DCI Roz Huntley (Thandie Newton) captures a serial killer, Forensic Coordinator Tim Ifield (Jason Watkins) alerts AC-12 to a possible miscarriage of justice.
Series four of the hit drama, written and created by Jed Mercurio, started with DCI Roz Huntley and her team in the thick of a career-defining case, Operation Trapdoor.
Under intense pressure to catch the culprit and prove herself to her superiors, and facing conflict with her colleague, Forensic Coordinator Tim Ifield, it’s not long before AC-12 decide to probe her handling of the investigation.
A mother of two and wife to husband Nick (Lee Ingleby), Roz will do anything to stop her life unravelling. Anything.
In tonight's episode, the explosive series finale pits AC-12 against Roz in a climactic duel to find Tim's murderer and unmask Balaclava Man.
In this preview clip, DS Railston & DCI Hargreaves question Nick Huntley about Tim Ifield's murder.
Meanwhile, Adrian Dunbar, who plays Superintendent Ted Hastings, has teased a shocking end to the show.
He told TV & Satellite Week magazine: "If you have watched the series from day one, there are still questions that haven't been answered.You never know what will come back to bite you on the nose!
"What Hilton is a part of hasn't been entirely resolved and we aren't sure if Ted knows more about that. Those things may turn out to be be red herrings, though."
Line Of Duty airs tonight at 9PM on BBC One.