The sixth series of Line Of Duty came to its long-awaited conclusion on Sunday night, with viewers finally learning the identity of the Fourth Man H.
However, despite fears this could be the show's last hurrah, millions of viewers were still left with unanswered questions, as the future of AC-12 was left hanging in the balance, and Superintendent Hastings feared for his future after confessing he revealed John Corbett was an Undercover Officer.
So, as fans wait to see whether Jed Mercurio's police drama could return for a seventh out, MailOnline examines some of the biggest mysteries AC-12 may have to solve.
We want more! The sixth series of Line Of Duty came to its long-awaited conclusion on Sunday night, but its conclusion left viewers with more questions than answersInsurance Loans Mortgage Attorney Credit Lawyer
Is it him? Despite the episode revealing that that Detective Superintendent Ian Buckells was actually the so-called 'Fourth Man,' some viewers were quick to note that he didn't confirm whether he was the leader of the Organised Crime Group
Who is the REAL leader of the OCG?
Despite the episode revealing that that Detective Superintendent Ian Buckells was actually the so-called 'Fourth Man,' some viewers were quick to note that he didn't wholly confirm whether he was the leader of the Organised Crime Group.
Instead, he pinned the blame on Tommy Hunter, who was killed back in series two, meaning Buckells' claims seemed less and less likely.
So the question still remains of whether another corrupt officer or criminal is still pulling the strings in the OCG, and Buckells' role as a middle-man means they could still be out to cause trouble for AC-12.
Really? Instead, he pinned the blame on Tommy Hunter, who was killed back in series two, leaving many viewers unconvinced by his claim
What will happen to AC-12?
Despite finally uncovering the identity of H through a long paper trail of corrupt officers, fans were surprised to learn the organisation's powers had been significantly weakened.Insurance Loans Mortgage Attorney Credit Lawyer
Fleming hinted she'd be open to taking her job back alongside Arnott and Hastings, who vowed to appeal his forced retirement despite confessing to DCS Patricia Carmichael he's revealed John Corbett's identity as an Undercover Officer.
Steve hinted he may take a break from active duty to overcome his addiction to painkillers, despite he and Kate appearing closer than ever as she told Occupational Health that he was 'the best.'
Despite this a final shot of the AC-12 elevator showed the trio reunited as they travelled down the lift together, hinting perhaps viewers get to see them together again, even though bosses have been tight-lipped on whether the show could return for a seventh series
Will Steve get together with Steph, or Kate?
Throughout the series viewers saw Steve form a close bond with John Corbett's widow Steph, even spending the night in her bed after continuing to struggle with back pain and his painkiller addiction.
But by the end of series six, he was clearly doubting whether to pursue a relationship with her, given how she lied about a vast sum of cash given to her by Hastings.
As series six concluded, it was clear that Steve and Kate had never been closer, as she described him as being 'the best' during a meeting with Occupational Health, and hinted she could be ready to return to AC-12.
Fans have long enjoyed the pair's close friendship but perhaps series seven could lead to something more.
Should we trust him? It's possible that Chief Constable Osborne could be involved in the OCG have openly dismissed any claims of corruption on the force, even after AC-12 discovered H's identity
Is Chief Constable Osborne bent?
For years CC Phillip Osborne has been a prime suspect in AC-12's investigations of corruption, and it was revealed this series that he worked on the Lawrence Christopher murder case now-deceased Marcus Thurwell, and 'H' Buckells
In a televised conference, Osborne commended the work of his officers in locating Gail Vella's murder, but once again dismissed any institutional police corruption as 'an outrageous lie.'
Given he is clearly willing to dispel any credible leads AC-12 may have, it's possible could be involved in an OCG, and may carry on doing their dirty work for years to come.
Line Of Duty: AC-12 FINALLY learn the identity of the elusive criminal H in shock series six finale - but fans are left 'underwhelmed' and convinced there has to be 'one more twist'
By Laura Fox for MailOnline
Line of Duty fans across the nation were left underwhelmed as the nail-biting series finale drew to a close tonight and the mysterious antagonist 'H' was finally unmasked.
Seasoned fans took to social media in their droves to share their frustrations as officers of the police anti-corruption unit AC-12 discovered that the identity of the elusive 'fourth man', who had been colluding with the organised crime group (OCG), was none other than DSU Ian Buckells.
The series also saw DI Steve Arnott, played by actor Martin Compston, finally called in for a meeting with Occupational Health, who noted that while he had not broken the law through his excessive painkiller use, he would have to surrender his firearms licence.
However, the episode's end failed to offer any resolution on whether the fan-favourite team of DI Steve Arnott, DI Kate Fleming and Superintendent Ted Hastings would return, ending on the revelation that the team has 'never been weaker.'
Sharing their disappointment on the ending, one disgruntled Line of Duty fan wrote on Twitter: 'Can't believe I watched six seasons of line of Duty for Ian Buckells, the most pointless character to be the fourth man. Fuming.'
At last! Line Of Duty's much-anticipated sixth series came to its conclusion on Sunday night with the identity of the elusive criminal 'H' finally unmasked
While another wrote: 'We waited 10 years for Ian Buckells to be revealed as the OCG mastermind.'
Another commented: 'Everyone in the UK when we waited all this time for Ian Buckells to be revealed as the OCG mastermind.
Meanwhile another fan said: 'I would have accepted Hastings as H over Ian bloody Buckells #LineOfDuty #LineofDutyFinale.'
During the episode, fans watched in anticipation as DI Arnott was left torn on whether to pursue fears that Hastings could be H as the team raced to uncover the mystery figure's identity.
The officer also admitted to his friend detective Kate Fleming that he had been involved with John Corbett's widow Steph.
After AC-12 discovered the OCG's workshop, they found a strong box hidden under the floor, which is revealed to contain an array of weapons used in murders investigated by Hastings and his team, including the gun that shot and killed Gail Vella, and the knife that slit the throat of DS John Corbett, who was killed by the OCG in series five.
It's the breakthrough that the team have been waiting for, as the box finally proves that Carl Banks was responsible for Vella's murder before being killed by the OCG himself.
Shocking: Viewers were noticeable underwhelmed to learn the identity of the elusive criminal, as the series ended on an ambiguous note
After weeks of incessant emails, Steve is finally called in for a meeting with Occupational Health, who note that while he hasn't broken the law through his excessive painkiller use, he should take time off from his duties.
To no surprise, Arnott refuses, but does agree to hand over his fire-arm, and comes to clean to Hastings about his drug use. To his, and the viewers' surprise, Hastings doesn't dismiss him, simply saying: 'I'm glad you're getting some help.'
Despite fans' theories that Thurwell had to be alive, it is