There's only one episode of to go and Line of Duty fans are still as baffled now as they were right at the beginning of the sixth series.
But one fan reckons that they've spotted a major 'H' spoiler that will be exposed during the finale - on actress Anna Maxwell Martin's Instagram account, no less.
Her vile character DCS Patricia Carmichael returned recently to announce that AC-12 would be merging with AC-9 and other units as cuts were made to anti-corruption.
Fans were also left devastated when it emerged that Ted Hastings was being forced into early retirement.
During Sunday night's episode, DCI Joanne Davidson was brought in for questioning and that laptop she had been messaging 'H' on was brought into question.
One huge clue throughout the series about H's identity is their inability to spell 'definitely', instead writing 'definately'.
As speculation began to grow that Carmichael, after her dodgy decisions on Friday and interrupting of Davidson's interview with Steve and Hastings, some fans were left a little sceptical.
One shared a picture of a stern looking Carmichael and tweeted: "If you seriously think Anna Maxwell Martin is H, ask yourself whether this is the face of someone who would misspell 'definitely' #LineOfDuty."
But another fan replied with eye emojis: "Apparently she does..."
Attached was a picture of Anna Maxwell Martin's Instagram post of her dog, but had captioned it: "Definately mama to this bank drain."
One stunned fan responded: "HOLY F*** SHE HAS BASICALLY TOLD US ALL."
While another exclaimed: "You just blew this case wide open!"
A third wrote: "GAAAAAHHH!!!"
Is Anna's comment a hint or just simply another red herring? We only have six days to find out...
*Line of Duty's final episode airs Sunday at 9pm on ITV
