Season six of Jed Mercurio’s police thriller comes to what’s sure to be a thrilling finale tonight (2 May), with many questions still to be answered.
Here are the burning questions on every Line of Duty fan’s mind...
Who is H?
The big one. ‘Person H’ is the mystery at the heart of the entire show. The shadowy “fourth man”. The corrupt cop who is leading the criminal syndicate known as H. The one who can’t spell ‘definitely’.
Theories abound as to who it could be. The suspicion has already fallen on Ted Hastings (Adrian Dunbar), but this feels too obvious for a playful writer like Mercurio.
This season, other candidates for ‘H’ include DS Joanne Davidson (Kelly Macdonald), Detective Superintendent Ian Buckells (Nigel Boyle) and the mysterious – and now presumed dead – former Detective Chief Inspector Marcus Thurwell (James Nesbitt).
If you want to really go down this rabbit-hole, here’s our TV writer Iain Leggat’s ratings of all the H theories.
Will Steve’s drug test come back to bite him?
How many times now as Steve Arnott (Martin Compston) dismissed an email about his drugs test? It’s been a running backstory of this season, with poor Steve heavily reliant on painkillers for his back injury from series four.
Surely this will come back to haunt him in the finale, as the cracks start to appear in AC-12. Will he be suspended at the crucial moment in the investigation?
Have we seen the last of Marcus Thurwell?
No British cop show would be complete without an appearance by James Nesbitt, but is that really all we’re getting from the Northern Irish actor? A mugshot, a grainy long-range photo and a badly burned corpse?
Fans have speculated that Thurwell isn’t really dead, and could yet make an appearance in the finale. Did one of the Spanish police really share Nesbitt’s distinctive eyebrows, or were our eyes deceiving us?
Will Ted Hastings be forced into early retirement?
DCS Patricia Carmichael (Anna Maxwell Martin) has stolen the show since she made her return to Line of Duty in season six - and she’s out to get AC-12.
Last week she said she didn’t trust AC-12 and had their vehicles tracked. But with Hastings already instructed to take early retirement after going after one too many “bent coppers”, is now the time where Carmichael will assume the reigns? “Mother of God”…
What will become of Jo Davidson?
It’s becoming likely that Jo Davidson is a relatively innocent bystander in the OCG (organised criminal gang) infiltration of Central Police - and last week’s revelation around her dark family history was truly shocking.
While suspicion looks set to fall elsewhere for the identity of ‘H’, will DS Davidson take the fall?
Who killed Gail Vella?
Let’s not forget the murder case at the heart of this series. Journalist Gail Vella (Andi Osho) was assassinated after digging dirt on the police links to OCG.
Carl Banks was overheard boasting in a pub about murdering the reporter before he was killed - but will we find out who really pulled the trigger?
Is this really the end for Line of Duty?
This has yet to be confirmed by the BBC, but there are some ominous signs that Ted, Kate and Steve will be teaming up for the final time tonight.
“Every investigation has led to this”, as the trailer goes, and if we do have conclusions to key questions such as ‘who is H’ then it will feel like a fitting ending.
But with more than 10 million tuning in every week, could the BBC find a way to extend it for a seventh series?
Line Of Duty ends tonight at 9pm on BBC1
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