Line of Duty viewers have been left gobsmacked after the infamous balaclava man was unmasked as an undercover copper in a sensational twist.
The identity of balaclava man has left fans guessing ever since he turned up to cause chaos in season four, viciously attacking Steve Arnott and getting involved with murders, abductions and cover-ups.
The masked man, who was thought to be one of many criminal thugs, was later revealed in a CCTV image which showed acclaimed actor Stephen Graham in the role of villain John Corbett.
He became a huge part of the show tonight as series five kicked off with Corbett's gang brutally murdering three police officers to steal a massive haul of drugs.
As leader of the gang, he was seen striking a deal with a drug lord to sell half the load, telling him bluntly: "We're facing life for murdering three coppers".
Who is Line Of Duty's balaclava man and This Is England actor Stephen Graham?
After WPC Maneet Bindra got involved with the plot, Corbett had her kidnapped and then gave the order for her to be disposed of after he found a bugging device on her phone.
So it came as a HUGE surprise to viewers at the end of the episode when he was confirmed to be an undercover police officer.
The AC-12 were finally clued in about a widespread undercover operation being led by Detective Sergeant John Corbett, with his picture and police file being flashed up onscreen to leave viewers in no doubt that the show's most hated villain is actually a good guy.
However, knowing the twists and turns of previous series, fans will have to wait and see if he really is a good guy or if spending so long undercover has turned him bad.
While viewers were shocked by the revelation, they went into meltdown over the horrific killing of Maneet Bindra at the end of the episode.
Thugs were shown slitting her throat in a graphic and bloody sequence that left may feeling queasy.
However, many pointed out that if Corbett really is a good undercover cop, he's unlikely to have ordered the killing of a colleague - many suggested he could have faked the murder and spared Bindra.
Line of Duty returns on Sundays at 9pm on BBC1.
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