But Sunday night’s episode of the hit BBC cop show saw two other characters meet their maker, as it was revealed Ryan Pilkington did not survive his and Fleming’s stand-off, while Marcus Thurwell was also found dead – or, at least, that’s what we’ve been led to believe.
Meanwhile, DCI Jo Davidson ended up behind bars when she admitted being forced by her uncle Tommy Hunter – who, in a dark twist, was also revealed to be her father too – to join the police force to serve the OCG from the inside.
The episode delivered a lot in terms of answers to previous questions, but our suspicions about DCS Patricia Carmichael have now reached new heights, as the hunt for the “fourth man” became more important than ever.
Ahead of what promises to be an explosive finale next week, here’s our final set of burning questions...
1. Why did Fleming flee the scene of Pilkington’s death?
We’ll be honest, we’re really not sure why Fleming decided to flee after shooting Pilkington dead – she would have been in the clear as there was an immediate threat to her life, plus she could have apprehended Davidson.
We’re guessing that Fleming still wanted to believe the best of Davidson, and was hoping she would lead her to more information about the investigation.
2. Who did Davidson believe her father was growing up?
The episode saw the truth about Davidson’s parentage revealed, when it was confirmed that Tommy Hunter was both her uncle and father, after he’d raped his sister as a teenager.
While Davidson found out later in life that her mother was sexually assaulted and then made to keep the child, she did not know Hunter was her father, and grew up believing another man was.
She didn’t disclose his identity to AC-12, but did tell Fleming that he was a bent police officer. Who was he? Could he have been Marcus Thurwell? Speaking of which...
3. What was Davidson’s relationship to Thurwell?
While we don’t know if Thurwell was the man Davidson believed was her father, she definitely knew his name and face.
She refused to comment to AC-12 about the nature of their relationship, and while it could just be that she’d encountered him through Hunter previously, the withholding of information points to something more significant.
4. So did Davidson not realise she was communicating with Thurwell via the laptop?
The IP address of the “Unknown User” who ordered Fleming’s death came from Spain, which is where Thurwell was residing, suggesting it was him who Davidson had been chatting with.
But did she know this at the time? We’re guessing not, and we’re certain that also has to be a point of note.
5. Why was Davidson willing to take the fall for Fleming?
Again, we still don’t understand quite why Fleming – who has had an exemplary service record up until now – didn’t come clean about Pilkington’s death. But the fact Davidson was willing to take the fall for her by planting her prints on Fleming’s gun makes us believe the pair might have had a personal relationship that we haven’t seen on screen.
After all, it’s been heavily hinted at since the first episode of the series, when Farida Jatri told Davidson she believed she’d been having an affair with Fleming.
We also know that Carmichael doesn’t believe Davidson’s version of events due to the shots fired at Pilkington being consistent with someone who has firearms training – which Fleming does and Davidson doesn’t. So surely it’s only a matter of time before Carmichael exposes the truth?
6. Why did Carmichael consistently steer questioning away from the wider investigation into institutionalised corruption?
Last week, we set out our belief that Carmichael could be corrupt and working with Chief Constable Philip Osborne, and now we’re more convinced of it than ever before.
Not only did she and Osborne have trackers placed on all of AC-12’s vehicles, she consistently batted away any of Hastings’ questions about the wider case during Davidson’s interview, and there has to be a reason for this.
Just what is she hiding? And will Hastings be able to get to the bottom of it before he’s forced into retirement?
7. Is Buckells really innocent on all counts?
During Davidson’s interrogation, it was revealed she had planted a number of things to make Buckells take the fall for her interference in Operation Lighthouse, including the missing files and the fudged surveillance authority at Beechwood House.
However, there were still question marks over a letter of recommendation Buckells supposedly wrote suggesting Davidson take over on the case from the previous ISO, as well as the story behind Deborah Devereux’s false witness statement.
Carmichael was keen to go with Davidson’s belief that Buckells simply used Devereux up to help get the case closed and advance his career, rather than him having any collusion with organised crime. But Carmichael’s drive to get Buckells off all charges makes us suspicious. Has she been working with him?
8. Will Arnott be suspended?
He’s on his final warning to attend his medical appointment, following the routine drugs test, and will be suspended if he does not attend within the next five days. Will he go and open up about his addiction issues before it is too late to save his career?
9. Is Thurwell actually dead?
After a Spanish operation to raid Thurwell’s address was carried out, officers found a male and female dead at the property, which we were led to believe was Thurwell.
However, the live footage from the bodycam was grainy to say the least, and we also never actually saw a face – so could it be that Thurwell is alive and he has been in collusion with someone in the Spanish police to stage his own death?
When it was reported that a scene from a future episode of Line Of Duty had leaked earlier this month, The Sun said the BBC Maestro website accidentally uploaded a scene where the face of a new character played by a top actor “could be seen on a database”, while “a short scene in which the character appears” was also shown.
Unless there’s another actor set to join the show in the final episode, we know this character to be Marcus Thurwell, played by James Nesbitt.
However, we are yet to see any scenes of James in action, which suggests Thurwell might still be alive and appear in the finale.
10. If Thurwell is dead, who ordered his murder?
There is only a limited number of people who were aware that AC-12 had uncovered Thurwell’s involvement in the wider case – Hastings, Arnott, Davidson, Bishop, Fleming, Carmichael and Davidson’s legal aides among them. This suggests that one of them passed information back to the top of the chain after Davidson’s interrogation.
Our theory is that Carmichael told Osborne, and Osborne ordered Thurwell’s death to protect himself.
11. What is under the workshop floor?
Fleming had suspicions something is lurking under the concrete floor of the gun workshop and ordered for it to be dug up. Just what will be found?
12. Will Davidson be killed?
While there’s CCTV surveillance on her prison cell to keep her safe, we know some of those prison officers are bent given their previous attacks on Lindsay Denton and Farida Jatri.
Will they find a way to stop Davidson revealing more about the “fourth man”?
13. Is Osborne the ‘fourth man’?
All things are certainly pointing at this being the case, but if we know anything about a Line Of Duty series finale, it’s that there will be a few twists and turns along the way...
Line Of Duty concludes on Sunday at 9pm on BBC One.