The police drama's thrilling fourth series pulled in its largest audience yet as the mysterious Balaclava Man was identified to be several people rather than just one culprit.
Writer Jed Mercurio told ITV's This Morning that reports the show will receive the Hollywood treatment were a "made-up story" as he confirmed viewers will have to play the waiting game before they get the answers to some of the burning questions left unanswered by the finale.
He said: "I hope it won't be too long, we are filming the next series next year but it will be in the second half of next year so there is enough time to get the script right and get the cast together.
"The earliest I can imagine it will be on air is early 2019."
One of the questions he has promised to answer is that surrounding Pc Maneet Bindra, played by Maya Sondhi, who shocked fans by appearing to betray her colleague in anti-corruption unit AC-12.
As Detective Chief Inspector Roz Huntley, played by Thandie Newton, tried to throw the investigating officers off the scent of her role in the death of Timothy Ifield, it was revealed Pc Bindra was handing over sealed information in dark alleyways.
She was last seen sneaking out on early maternity leave without saying goodbye to any of the colleague she had secretly betrayed and Mercurio said he knows fans need answers.
He said: "It's great people have responded to that, we owe it to the audience to tell them more about what was going on."
Sondhi added: "I didn't know that was coming, that was a massive surprise to me and when I read that episode and got to that scene, when she hands over the stuff, I said 'Have I seen that right?' and kept asking Jed 'Why is she doing this?'
Mercurio also hinted Superintendent Ted Hastings (Adrian Dunbar) could suffer the consequences of shooting dead one of the Balaclava Men rather than trying to capture him alive.
He said: "It could possibly come back and haunt him, only possibly."
He added: "Those are the things we put in the series and we hope people will say 'hang on a second, should he have done more to capture that person?'
"Balaclava Man has an interesting tale to tell, he can point the finger at higher up people and potentially break this open, but was it just the heat of the moment and he was protecting his officers?"