HIT cop drama Line of Duty is returning to deliver the explosive climax denied fans in the last series.
Stars Adrian Dunbar, Vicky McClure and Martin Compston are on board for the three-part BBC1 special.
A TV insider said: “There’s a strong feeling that there was unfinished business.”
Fans of the show will hope bent copper H is finally unmasked when three new episodes of the smash-hit cop drama are shown next year.
Many of the 13million who saw the sixth series felt it a huge anti-climax to learn buffoon Det Supt Ian Buckells (Nigel Boyle) was the elusive mastermind with links to organized crime.
Fans were left wondering if it was a genuine end after nine years of nail-biting storylines, or a red herring by creator Jed Mercurio.
Main cast Martin Compston, 38, Vicky McClure, 39, and Adrian Dunbar, 64, are on board to return as the heroes of AC-12 with a view to filming from spring.
The final three parts could be shown as early as next Christmas.
A TV insider told The Sun: “There was a very strong feeling, particularly among fans, that there was unfinished business with Line of Duty.
Viewers weren’t satisfied with the ending of series six and were crying out for a more sensational conclusion — now Jed can deliver that.
“The question is whether the person we were led to believe was H really the villain that AC-12 has been hunting or if it was another nemesis.
There’s also a theory another, darker puppet-master is at work.
“The fact that they’re looking at taking the unusual step of making three episodes rather than the usual six or seven is a reflection of just how special this is for the show.”
Writer Jed, 56, has never ruled out returning to the story.
And leading stars have recently dropped increasingly strong hints about a comeback.
Vicky, who plays DI Kate Fleming, told Good Morning Britain on Tuesday: “I speak to the lads all the time and we’d all love to, we’re all game.
“I think it’s just a case of now. . . Martin, I think he’s in about nine shows or something. He’s busy, so I’m sure we’ll get there.”
Martin — DI Steve Arnott — said of Line of Duty last week: “I’m so chuffed that people want it back.
But who knows? I’d love to work with the guys again. Adrian, Vicky and Jed are genuinely some of my closest friends.
“It’s been ten years together and we speak every other day, really.”
Adrian, much loved for Chief Supt Ted Hastings’ sayings such as “Jesus, Mary and Joseph and the wee donkey”, currently has his own ITV police show, Ridley.
Vicky is starring in Without Sin and has a second series of ITV’s Trigger Point coming up.
Coordinating their diaries could have proved tricky which is why bosses are looking at three episodes.
Adrian said a few weeks ago: “I think generally there’s a willingness amongst everybody to do something but I think we’re just going to have to wait a little bit longer.”
He said the cast were keen for a final outing because series six was made under lockdown constraints.
Adrian added: “It wasn’t quite as fun. We couldn’t hang out. We couldn’t go out.
“We were all in a kind of bubble so it just didn’t have the same feel — which is one of the reasons we’d like to do another one.”
The BBC declined to comment.