AC-12s three main faces have always been Superintendent Ted Hastings (played by Adrian Dunbar), DI Kate Fleming (Vicky McClure) and DI Steve Arnott (Martin Compston). As the main trio of Line of Duty since the first series, they have led the investigations into the Organised Crime Group (OCG) and uncovered several corrupt officers. But is it possible that Steve himself could be involved?
One Reddit user explained a plausible theory surrounding Steve - that he's in fact part of the OCG.
The fan said they believed Philip Osborne (Owen Teale) would be revealed as H, but that Steve would be an unexpected twist.
They said: "My theory is Steve has been in cahoots with Osbourne the whole time.
"What if the failed anti-terrorism operation at the beginning of season 1 was simply a way of planting Steve within AC-12, with Osbourne having Steve tell the truth in regards to the operation, against the fabricated stories of his colleagues, to win the trust of Hastings."Insurance Loans Mortgage Attorney Credit Lawyer
READ MORE: Marcus Thurwell exposed as H in Line of Duty
Line of Duty theory: Is Steve in the OCG? (Image: BBC)
Line of Duty: Could Steve be H? (Image: BBC)
They went on to speculate that Steve's questionable actions throughout the series, such as sleeping with Lindsay Denton (Keeley Hawes) and co-operating with John Corbett (Steven Graham), despite his hatred of Hastings and more, could have been a deliberate scheme to discredit AC-12.
The Reddit post concluded: "The one piece that doesn’t fit is Balaclava man attacking Steve in season 4, but as Davidson said, the OCGs after the death of Tommy Hunter became fragmented, and perhaps Steve’s OCG links are unknown to other OCG members such as the Huntley office Balaclava man and Dot."
Could Steve really be leading a double life, hidden from viewers all this time?
Currently, Osbourne is the favourite prediction among fans to be exposed as H.
Line of Duty: Ted Hastings often rises suspicions (Image: BBC)
Line of Duty: Could