Line of Duty creator Jed Mercurio has teased fans with a massive 'H' bombshell.
The identity of corrupt copper at the top of the pyramid has become the hit BBC drama's biggest mystery.
Mercurio has revealed he has been planning a shocking twist since the start of the show, which is currently in it's fifth series.
Viewers have been comes up with theories and attempting to predict who 'H' really is - but Mercurio has revealed he could change his mind.
He explained that he has given several characters names that can be turned into 'H' to create a host of suspects.
The show's creator told the BFI & Radio Times Television Festival: "I suppose if I had an idea later on that was even better then, yeah, of course I would change it.
"Because you want it to be as good as possible and surprising and so forth."
Line of Duty fans still don't know who 'H' is after watching the first two episode of the new series.
Superintendent Ted Hastings is one of the prime suspects, but viewers have threatened to boycott the show if the fan favourite is the big baddie.
Mercurio revealed he is playing with viewers by deliberately creating red herrings.
He said: "Sometimes there were characters whose name could be corrupted or nicknamed into being an 'H' if I wanted to.
"Some of the characters were given names where they could have been revealed as having an 'H' connection if it was required."
Mercurio has also revealed when the last series will be - but expect plenty of twists and turns along the way.
A sixth series has already been commissioned, but Jed is hoping that the thrilling police drama will finish with series 7.
AC-12 usually take a two-year break between series and the ending of each is deliberately written to set up future storylines.
Jed said: "Once series five has finished airing we’ll have a conversation with the BBC, with a view to whether there’s a possibility to series seven being commissioned.
"But we definitely know we’ve got series six.
“The only reason is that there are a lot of loose ends to tie up, and we couldn’t take the risk of getting it commissioned later on.
"So if we didn’t know that we could go beyond this series, then we would have to approach it in a way that concluded things."
*Line of Duty airs Sundays on BBC One at 9pm
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