Line Of Duty: 8 Things The Series 6 Finale Absolutely Must Deliver

It's not just answers about "H" and "the fourth man" we're hoping for, either.

“Every investigation has led to this.”

After six weeks of intense drama, Line Of Duty is about to air what could be its most significant episode ever, as the hunt for “the fourth man” – otherwise known as “H” – reaches its climax on Sunday night. 

It’s the moment fans of the hit BBC cop show have been waiting more than four years for, as the first mention of “H” goes as far back as series four. 

If the finale plays out in the way many are hoping it will, it means that not only will another corrupt officer be unmasked, but various story strands from the show’s 10-year history will get tied up, along with many other loose ends from the current series. 

Here’s what absolutely has to be included in the blockbuster episode...

1. A resolution to Davidson’s story

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BBC

If there’s a phrase we’d happily never hear again after that penultimate episode, it’s “no comment”.

DCI Jo Davidson’s AC-12 interrogation didn’t exactly deliver much in the way of fresh information about the elusive character, her motivations or her connections to the OCG beyond her blood links to Tommy Hunter. As a result, her story feels somewhat incomplete. 

Who did she believe her father was? What’s her connection to Marcus Thurwell? Why has she taken the rap for Pilkington’s death?

From the series finale trailer, it looks like there might be something in the way of a conclusion for Davidson, as she is seen being transferred in a van with a corrupt prison officer. 

This suggests she could meet the same fate as her birth father. Hunter was killed in series two, when bent officers staged an ambush on his police convoy to stop him revealing their identities, after he’d agreed to co-operate with police in exchange for witness protection. 

Hopefully Davidson manages to speak out before any attempt on her life. 

2. Answers about Hastings

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BBC/World Productions/Steffan Hill

Question marks have been hanging over Superintendent Ted Hastings since the end of series four, and to be honest, we’re a bit tired with constantly having to suspect the gaffer of dodgy dealings. 

While we’re pretty sure he isn’t “H” (that would certainly be a controversial choice, given that was pretty much the whole point of series five), there are still unanswered questions about his contact with Steph Corbett. 

We know that he ratted undercover officer John Corbett out to OCG member Lee Banks, and following Corbett’s death, Hastings paid Corbett’s widow £50,000 of the money bent former officer Mark Moffatt had attempted to bribe him with. 

DI Steve Arnott has since become aware of this over the course of the series, but he and DI Kate Fleming are still sitting on what he’s learned. 

Our theory is that Hastings was a lot closer to Corbett’s mother, Anne-Marie McGillis, than he previously made out, and was actually Corbett’s father, subsequently paying Steph money out of guilt for inadvertently causing his own son’s death. 

But whatever the truth is, we really don’t want this to drag on into the next series. 

3. Arnott’s addiction storyline being developed

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BBC/World Productions/Steffan Hill

Arnott’s addiction to prescription medication after being pushed down the stairs by one of the balaclava men has been quietly playing out in the background of the last two series.

However, with Arnott now facing suspension from the force unless he attends a compulsory medical appointment, he risks losing his job unless he opens up about his struggles with addiction.

This suggests that this plot will soon reach some sort of turning point, but it remains to be seen if they find enough time to squeeze it into what’s likely to be an already jam-packed finale.

4. An explanation about why Fleming fled

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BBC

If there’s one thing fans could agree on after the penultimate episode, it’s their confusion surrounding why Fleming did a runner with Davidson from the scene of her stand-off with Ryan Pilkington, when Davidson had literally just lured her there to be killed.

Not only did it not make a huge amount of sense, it also felt very out of character for Fleming, who has always been such an exemplary officer. 

There are a number of theories behind Fleming’s motives – one of them being a supposed romantic relationship between the two women – but whatever the explanation, it feels significant, so we need answers.

5. Lots more Carmichael 

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BBC/World Productions

Love her or loathe her, there’s no denying DCS Patricia Carmichael has been one of the stand-out characters of the series.

Her delicious devilishness has been a joy to watch (even if it has been a real thorn in Hastings’ side), and we’re hoping Anna Maxwell Martin’s formidable character gets lots more screen time (and generates lots more memes) as the series wraps up

6.  Marcus Thurwell finally being introduced

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BBC

Now, we know what you might be thinking: “Errr, didn’t they kill off Marcus Thurwell in the last episode?”

Earlier this month, The Sun reported that a “top actor” was joining the show after the BBC Maestro website accidentally posted two scenes featuring the star in question that would appear in the show that upcoming weekend.

The paper described how the face of a well-known actor “could be seen on a database being searched by DI Steve Arnott”, while another “short scene in which the character appears was also shown”.

However, we’ve yet to see James Nesbitt – who plays Thurwell – actually appear in the show, as so far, his character has only been seen in pictures and mugshots. Therefore, it would suggest there’s at least one scene we’ve yet to see that features James as Thurwell. 

Some fans have also spotted something familiar about one of the armed officers that carried out the raid on Thurwell’s property, believing that it was actually the man himself. 

Therefore, fans need conclusive proof Thurwell is actually dead, or a scene that confirms he’s alive. 

7. A “definite” answer about “the fourth man”

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BBC

OK, this is the big one, and we’re pretty confident that we’re finally about to get to the truth about the artist-formerly-known-as “H”. 

After the hunt for him in the last series saw Hastings framed, a twist in the tale then took the case in a whole new direction, meaning we’ve had to wait a whole other series to find out which high-ranking officer has been helping to lead a network of corrupt coppers in collusion with the OCG. 

However, the series finale trailer teases that “every investigation has led to this”, as it lines up key suspects Carmichael, Hastings, Fleming, Thurwell and Chief Constable Philip Osborne. 

This “definitely” suggests that answers are coming, and we’ll be seriously disappointed if we don’t get them. 

8. Something that sets us up nicely for series 7

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BBC

Even if there is something to be said about going out on a high, we absolutely cannot entertain the idea this being the last we see of AC-12. 

Luckily, with Line Of Duty setting ratings records for the BBC, we can’t see the broadcaster letting creator Jed Mercurio kill off their most popular show, so we’re probably safe – for now at least. 

Therefore, we need a new strand of the story that will set us up nicely for series seven – and one that hopefully has nothing to do with “H”, Morse code or Hastings’ conduct. 

Line Of Duty concludes on Sunday at 9pm on BBC One.