Millions of us will be on the edge of our seats for the Line of Duty season finale on Sunday night, hoping finally to find out who H is.
And celebrity fans are no different – each with their own ideas about the identity of the “fourth man” and desperate to hear Ted Hastings’ best one-liners.
BBC Breakfast presenter Dan Walker has even booked Monday morning off work so he can stay up late to watch the show live.
Theories about which coppers are bent, who is part of the OCG and who killed Gail Vella have been flying around for weeks.
So what will become of Hastings, Steve Arnott and Kate Fleming?
As we swot up on our LoD acronyms and get set for some big revelations, we’ve turned to our celeb superfan panel – and the Mirror’s telly gurus Sara Wallis and Ian Hyland – for help.
Here, they give us their thoughts on what will be revealed as the sixth series comes to an end.
So whose instincts could get them a job in AC-12? Who’s following a dead end lead?
And who’s so far off the mark, they’ll find themselves on traffic duty?
Dan Walker - BBC Breakfast presenter
"I need to give it my full attention so I’ve taken Monday off so I can concentrate.
"For starters, I don’t think Marcus Thurwell is actually dead. Would you really recruit Jimmy Nesbitt to the biggest show on TV and limit him to two photos and a dead body shot? He’s got a role to play.
"As brilliantly annoying as DCI Patricia Carmichael is, I think she’s more of a greasy pole climber than a bent copper.
"I know there was the Morse code pen tap in the last episode (four taps for the letter H) but I’m convinced she knows how to spell DEFINITELY.
"I can’t sanction Kate Fleming being a wrong ’un, I’m sure Steve Arnott’s dodginess doesn’t extend beyond strong paracetamol and if Hastings is the bad apple I’ll be out of town on the first “wee donkey”.
"All roads seem to lead to Chief Constable Osborne (left) as the fourth man. The crucial evidence is lying under that concrete floor.
"Is it drugs, dirty cash or a dead body that links him to the OCG?
"I need closure as I can’t take another night worrying about what those two menacing prison guards are planning to do to Jo Davidson."
Lisa Riley - Emmerdale's Mandy Dingle
"I absolutely love the show. Every Sunday night I sound my one-hour-before klaxon to start reading Twitter to see what theories people have.
"I definitely think Chloe Bishop is corrupt on every level. I may eat my words but she seems to be involved in everything – handing over blue files every five minutes.
"She was the one who discovered the Spain link, and I also think she is the one who has shopped Steve Arnott to occupational health about his painkiller addiction. I think she wants rid of him.
"There is no way that Ted Hastings is H – he is the lynchpin of the whole show. It just can’t be him.
"I also think Steph Corbett is heavily involved somewhere. Maybe she is part of the OCG, or I have even thought that she may be Jo Davidson’s aunt, her mum’s sister, and she is involved to get justice for her.
"Mind you, one of my theories was blown out of the water last week as I really thought Kate and Ryan had killed Jo. But now I think there is more to come out about the Kate and Jo connection.
"No matter what happens, I just can’t wait for Sunday night like the rest of the nation."
Amanda Barrie - Ex-Coronation Street star and crime writer partner, Hilary Bonner
"OMG! Line of Duty we love you – but what have you done to us? Our brains need an upgrade.
"Who is H? That smug DCS Carmichael? Hastings? Surely not. It’s someone powerful with a finger in every pie. Ah. Got it. Mary Berry!
"Is Thurwell dead? Definitely not. Sorry – definitely. He got cold feet.
"But we spotted him recently in Belfast. Still looking dodgy.
"Who is Jo Davidson’s dad? Jim Davidson? Creator of Boobs in the Wood and a Charlton fan? Two facts which would understandably make Jo reluctant to admit her parentage.
"Is Kate Fleming a mole? No. She’s a hamster. Although she doesn’t seem to know how to stop digging.
"Will Gail Vela’s findings come to light? Apparently Piers Morgan is on the case. It’s why he left GMB.
"Is Steve Arnott a druggie? He certainly needs a line of something.
"What we need is Miss Marple to sit down at that table with a nice cup of tea and explain it all to us."
Hilary Bonner's new thriller Dead Lies begins a nationwide theatre tour this September. Visit deadlies.co.uk
Ian Hyland - Daily Mirror TV Critic
"Given what I do for a living, you’d be forgiven for thinking I’ve had some insider information.
"Not a bit of it. The security at the BBC ahead of this Sunday’s finale has been tighter than one of DCS Carmichael’s patronising smiles.
"My gut feeling is that the mystery won’t be solved at the weekend. I reckon Jed Mercurio and the BBC can just about get away with wringing another series out of the H/Fourth Man saga.
"You don’t want gut instinct though, you want wild theories. So here I go…
"DCI Tony Gates is still alive, despite clearly stepping out in front of a speeding truck in series 1.
"Tony used all the information he’d extracted from Tommy Hunter to engineer a situation where he became the head of the criminal gang.
"It’s so obvious when you think about it. OCG doesn’t stand for Organised Crime Group. It stands for Organised Criminal Gates.
"Don’t ask me how Mercurio will explain this one away, but in the past he has had us believing that a dying Dot Cotton left a Morse code message with his twitching fingers and that Kate Fleming had never batch-cooked chilli con carne in her life.
"So anything’s possible."
Victoria Ekanoye - Coronation Street star
"Line of Duty has a dream-team cast and is one of my fave shows of all time.
"For a while now I’ve thought Hastings was the Fourth Man – poetically ironic as he is an absolute ledge.
"Then my suspicions slithered towards Andrea Wise as she always seems to be working against AC-12 rather than with them.
"Plus she teamed up with Patsy Carmichael – I do not trust her – to invest-igate our Ted.
"Ultimately, I am totally gutted, though, because finding out who H is means it is the end of the show and, deep down, I think it might be Kate.
"She’s my absolute fave, but she just seems too good to be true.
"On top of that, she works undercover so has ample opportunity to infiltrate both the criminal and police world.
"True to fashion though we’ll all be wrong and it will be Steve Arnott!
"I can’t wait for the finale."
Sara Wallis - Daily Mirror TV Columnist
"Look, we’ve been round the houses and down the bloody drains, but after six mind-boggling episodes, my brain is not exactly sucking diesel on this one.
"But this is the urgent exit from series six that I’m expecting. Now I know the footage was grainy, but I think Marcus Thurwell and his missus are indeed dead. It would mean an anti-climactic cameo from James Nesbitt.
"But other guest stars also burned bright and briefly like Jessica Raine (chucked out of a window), Daniel Mays (shot dead within an hour).
"Unless we’re heading for an OCG on the Costa del Sol spin-off? I think Thurwell ordered the hit on Gail Vella and is Jo Davidson’s ‘other dad’, messaging her as Unknown User.
"There’ll be evidence under the workshop floor and DS Chris Lomax is bent, as is Chief Constable Philip Osborne, who is revealed as H. Steve is suspended and checks into rehab, Kate is Jo’s prison penpal, AC-12 hangs in the balance.
"Final scene? Innocent Ted, forced to retire, heads to the golf course… maybe he’ll need a caddy? Oh mother of God, here we go again… "
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