The season focuses on Ted Hastings (Adrian Dunbar), Kate Fleming (Vicky McClure) and Steve Arnott (Martin Compston) looking into the conduct of Joanne Davidson (Kelly Macdonald) during a murder investigation.
As well as this, they will also try to weed out the elusive ‘H’, a corrupt senior officer who has ties to criminal gangs.
At the very end of series five, all signs were pointing to Hastings but Kate and Steve worked tirelessly to clear him of all allegations at the last minute.
But, with new episodes kicking off, will we ever find out who H actually is?
What theories are there about H in Line of Duty?
There have been some wild theories about the identity of H, some of which are overreaching, while others have a little more weight to them.
The end of series five saw Steve and Kate looking closely into Matthew ‘Dot’ Cottan’s dying declaration and noticing he tapped his fingers in morse code four times, signifying that there are actually four ‘H’ officers in the force.
With that, our minds were totally blown
Three of them have already been identified – Derek Hilton (Paul Higgins), Gill Biggeloe (Polly Walker) and Cottan, which means one more is still out there.
A trailer for season six put Kate squarely in the frame for the criminal mastermind, as she is seen in a tense police stand-off.
There are also theories all over Reddit putting the pieces together, claiming creator Jed Mercurio has been throwing in easter eggs for this since Line of Duty began.
In fact, viewers have suggested all the nights she was ‘working late’ and ducked into her home after her family were in bed were a cover for her criminal activity.
Elsewhere from the AC-12 crew, fans have already suggested DCC Andra Wise (Elizabeth Rider) could be H, after she was so determined to keep the gang as far away from Operation Pear Tree as possible – with many adamant that they were getting too close to her identity.
DCS Patricia Carmichael’s (Anna Maxwell Martin) name has also been bandied about in the hunt for H, with social media users insisting that she led the investigation into Hastings in series five in a bid to cover her own back.
Do they have a point? Or were we all closer with the building theory?
Does H in Line of Duty really exist?
While some Reddit viewers have intense theories on exactly which member of the force H could be, others have taken things in a totally different direction, with user Sholista previously offering up their reasoning as to why there is no H.
‘My theory: there is no single person who is H,’ they began. ‘The reality is that corruption is so endemic in the force, with so many senior officers involved or with knowledge of it, that allowing the full extent of it to be revealed would be so catastrophic it would destroy faith in the police.
‘Gill makes reference to this in series 3 when she talks about the need for the anti-corruption units to prove a certain amount of corruption to keep up appearances, but not too much.
‘So there is political pressure, involving the PCC and therefore Gill as his lawyer, to bring closure to the investigation.’
The user continued: ‘They have been working to set up Ted as a scapegoat and frame him as H so that justice can appear to be done and the matter swept under the carpet.
‘It’s also likely that Ted himself has been involved in the plot to cover up corruption, and this could backfire on him as he tries to prove his innocence.’
Does Anna Maxwell Martin play H?
Anna Maxwell Martin’s character, Patricia, has been mentioned as a possible H – and she didn’t actually discount that theory during a chat with Zoe Ball on BBC Radio 2.
Spilling the beans on the theory, she joked: ‘It could be me! Pat “Harmichael” – I could be “Hat Harmichael!”
Stranger things have happened in the drama.
Line of Duty series six kicks off on Sunday, at 9pm, on BBC One. Series one – five is available to stream on iPlayer now.
MORE : Line of Duty’s Adrian Dunbar reveals Ted Hastings’ iconic one-liners weren’t scripted
MORE : Line of Duty stars on how series 6 was changed due to coronavirus pandemic
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