As the sixth series of Line of Duty reaches its nail-biting finale on Sunday, fans hope they will finally discover the identity of criminal mastermind “H”, or the “fourth man”.
Could it be one of the more obviously bent coppers, or will there be another breathtaking twist?
We examine the suspects alongside investigator and former detective Mark Williams-Thomas, who exposed Jimmy Savile as a paedophile in the TV documentary The Other Side Of Jimmy Savile, to see who is in the frame...
Fans hoping for answers to big questions in Sunday’s finale will not be disappointed, says star Martin Compston.
Martin, who plays DI Steve Arnott in the long-running police drama, said: “All I can say is I think there are a lot of pay-offs coming this Sunday.
“There’s a lot of big answers that are coming. People have stuck with us for such a long time and I think there comes a point where the natural story arc that has been running all these years is coming to an end.”
The penultimate episode of series six last Sunday was the most-watched instalment to date, with an average of 11 million viewers – and this weekend’s audience could be even bigger. But asked if show creator Jed Mercurio is planning a seventh series, Martin told the Shrine of Duty podcast: “The genuine answer is ‘we don’t know’.
“We won’t do one just for the sake of doing it. Jed will only do it if he feels there’s a story there to be told.”
Martin appears alongside co-star Vicky McClure, who plays Line of Duty’s Kate Fleming, on The Jonathan Ross Show tomorrow.
DCS Patricia Carmichael
Suspicions grew when Carmichael removed surveillance on PC Ryan Pilkington, which almost got DI Fleming killed in a gun fight.
And, as she and Hastings questioned Davidson, she seemed determined to stop any questions being asked about her boss.
Mark says: “Her character is deeply unpleasant and highly ambitious. I don’t think she has any moral compass. Being a police officer for her is about fulfilling her aim to get right to the very top.”
But he doesn’t think she is H. He says: “She’s too obvious, I don’t think she’s senior enough, and she doesn’t have the capacity to be cunning, sly or clever. And clearly whoever H is is sly and cunning.”
CC Philip Osborne
From the very first series, Osborne has been no stranger to a botched investigation – or lying.
He also desperately hates Hastings and forced through his retirement to get him out of the picture.
Mark says: “There’s no doubt he’s a bent copper and he’s risen through the ranks and been protected until he got to the top. He’s totally corrupt, totally wrong. He’s got links to organised crime. He’s got links to corruption – particularly with the murder of Lawrence Christopher.
“He’s in my top three suspects. However, he’s risen through the ranks and I think H has been towards the top from the start.”
DCI Marcus Thurwell
Thurwell was involved in both cases journalist Gail Vella was looking into before she was murdered.
He had retired and moved to Spain, but last Sunday two dead bodies were found in his villa during a police raid.
Mark says: “He’s in my top three. Is he dead? Or was it a stooge and set up in order for him to have an alibi and get away? He’s the perfect person. He’s in the perfect location to be running organised crime.
“Of course, we’ve got the link between the IP address linking back to Spain but he’s clever and wouldn’t leave behind a trail like that.Thurwell slightly pips it over Osborne for me.”
Det Supt Ian Buckells
When Buckells ended up in jail he was warned in no uncertain terms to keep his mouth shut.
Mark says: “I don’t think he was particularly clever, he was just being used by OCG.
“They probably had some dirt on him. He’s pocketed money and been helped in terms of a bit of promotion as well – he was certainly promoted above his ability. He’s not H.”
PCC Rohan Sin dwhani
Sindwhani has always been keen to downplay police corruption and protect the reputation of the force – especially with relation to Operation Pear Tree.
Mark says: “For a long time I did think he was a bit of a player in this. If I had to rank it then I’d put him as my number four suspect.
“I’ve always disliked him. It may simply be because he focuses on politics rather than policing. But there’s something about him that makes me wonder if there’s more to it.
“I’d love to dig deeper into his associations and who he knows and who he has contact with.
“He’s a bigwig but we don’t know much about him.”
DCC Andrea Wise
Sindwhani’s right-hand woman has given fans several reason to believe she might be H, but Mark just thinks she’s doing her job. He says: “I don’t think she’s bent.”
Acting Det Supt Jo Davidson
Jo was revealed as the daughter of crime boss Tommy Hunter and has been working for the OCG.
She planted burner phones in Farida’s house, framed DI Ian Buckells and diverted an armed convoy on the way to arrest a suspect over Gail Vella’s murder.
Mark says: “We know she is bent and that she was recruited by OCG.
“She’s got links through her family and she’s become a source for OCG for how Pilkington was working. But she’s absolutely not H because she’d have to have been talking to herself on the computer.
“Of course, the biggest question is now she’s in prison, will she live?
“I doubt it.”
DI Kate Fleming
One of the less obvious contenders for H, Fleming currently has 20/1 odds to be unmasked as the “fourth man” working for the OCG.
But could this be the biggest plot twist of all?
Mark doubts it.
He says: “She’s lovely. Her guard came down when she left AC-12 and she wanted to leave that all behind her.
"She was clearly divided in terms of who to support and I think she made some wrong decisions, such as supporting Davidson.”
Supt Ted Hastings
Ted has devoted his life to anti-corruption but he has been acting strangely this series, with a meltdown in the lift and secretly giving DI John Corbett’s widow Steph £50,000 in cash.
Mark says: “There’s a very fine line between right and wrong and sometimes he does cross over it, especially with regards to the money and to giving up the undercover officer. But he’s done all of that because he cares and wants to catch the baddies.”
He adds: “Is he H? No, I genuinely don’t think he is and the public would be mortified if he was.”
DS Chris Lomax
Quiet copper Lomax who has been working on the Gail Vella case could be corrupt but Mark doesn’t suspect he’s H.
He says: “I definitely think he’s part of the OCG. He’s quiet and he’s a good eyes and ears but he’s not H. He’s not senior enough.
“In the police the more senior officers have more power, more influence and crucially they’ve got more access to information. And for H information is absolutely key.”
Or is H a curveball?
Mark thinks the real H could have gone so far under the radar that viewers don’t suspect them at all.
He says: “It may be somebody who is not in the frame but is on the periphery. We’ll have seen them a few times over the six series but they’ll come in completely left field. I just don’t know who it is.”
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*Line Of Duty airs its thrilling finale on Sunday at 9pm on BBC1
