Line Of Duty series 6 SPOILER: Kate Fleming and Steve Arnott look tense during shoot-out

Line Of Duty fans are waiting with bated breath for the explosive series six finale this Sunday – in which the infamous ‘H’ is set to be unmasked.

And a new photo from the police drama’s finale episode will only heighten speculation the OCG is set to be taken down by AC-12, with DI Kate Fleming (Vicky McClure) and DS Steve Arnott (Martin Compston) looking tense during a shootout.

The dynamic officers are both clad in bulletproof vests and brandishing guns as they stand on a residential street by a van – with a tense Steve talking into a police radio.

They’re sucking diesel now! A new photo from the Line Of Duty series six finale sees DI Kate Fleming (Vicky McClure) and DS Steve Arnott (Martin Compston) looking tense during a shootout.

In the background, former AC-12 officer Kate looks frightened as she stares into the distance.

Eagle-eyed fans will note that Kate is wearing the same grey turtleneck jumper and Steve the same grey suit as in set images of the show from October 21 – where Kate and Steve were seen having a heated conversation with Ted Hastings and the gaffer dramatically exited the station. 

The snaps, believed to be taken during filming of the seventh episode of the series, show a concerned Kate and Steve standing united as they speak to Superintendent Ted Hastings. 

Same outfits: The new photo sees Steve and Kate wearing the same outfits captured in images from the Belfast set of Line of Duty, taken during filming on October 21 last year

Same outfits: The new photo sees Steve and Kate wearing the same outfits captured in images from the Belfast set of Line of Duty, taken during filming on October 21 last year

There have already been cracks appearing between the AC-12 trio after Steve discovered that Hastings blew John Corbett’s cover – which resulted in John having his throat slit by Ryan Pilkington – and seemingly gave his widow Steph £50,000.

In the tense images, Kate looks worried as she stands with her arms folded alongside Steve, while Hastings stands some distance away from the duo looking sombre.

Hastings, who has already become exasperated with time running out before he’s forced into retirement and AC-12 is disbanded, is also seen rushing out of a police car as things heat up.

Coming back: Line Of Duty will be back on Sunday night and fans are eager to find out whether AC-12 will finally crack the case on the elusive H

Coming back: Line Of Duty will be back on Sunday night and fans are eager to find out whether AC-12 will finally crack the case on the elusive H

Trailer: In a teaser released on Monday, viewers can be certain of an action-packed finale episode with a police standoff, the return of balaclava men and that 'definately' misspelling

Trailer: In a teaser released on Monday, viewers can be certain of an action-packed finale episode with a police standoff, the return of balaclava men and that ‘definately’ misspelling

While another snap showed a stony-faced Hastings pointedly walking out of the front gates of Decker Avenue Police Station, where former solicitor Jimmy Lakewell was taken before withdrawing his cooperation with AC-12 and subsequently getting murdered at HMP Blackthorn.

The photos will leave fans wondering if Kate and Steve are going to confront Hastings about the mysterious wad of cash given to Steph, as well as what the trio are doing at Decker Avenue Police Station. 

The new photo comes two days after a new trailer for Line Of Duty’s finale was released, only serving to heighten speculation around the identity of ‘H’.    

AC-12: The trailer starts off with Superintendent Ted Hastings (Adrian Dunbar), state: 'All of these suspicious deaths were orchestrated by one officer in particular, H. The fourth man'

AC-12: The trailer starts off with Superintendent Ted Hastings (Adrian Dunbar), state: ‘All of these suspicious deaths were orchestrated by one officer in particular, H. The fourth man’

Fall from grace: The trailer then shows acting Superintendent Jo Davidson (Kelly MacDonald) leaving the high-security prison in handcuffs

Fall from grace: The trailer then shows acting Superintendent Jo Davidson (Kelly MacDonald) leaving the high-security prison in handcuffs

Scary: She ends up alone in a van with a corrupt prison officer who previously injured Lindsay Denton in series three

Scary: She ends up alone in a van with a corrupt prison officer who previously injured Lindsay Denton in series three

Clue: A handwritten note is also teased in the trailer, with the word definite misspelt to mirror what viewers have seen previously- will this be the clue AC-12 needs?

Clue: A handwritten note is also teased in the trailer, with the word definite misspelt to mirror what viewers have seen previously- will this be the clue AC-12 needs? 

Viewers can be certain of an action-packed finale episode complete with a police standoff, the return of balaclava men and the discovery of a written note with THAT ‘definately’ misspelling. 

The trailer starts off with Superintendent Ted Hastings (Adrian Dunbar), who is facing imminent retirement, state: ‘All of these suspicious deaths were orchestrated by one officer in particular, H. The fourth man.’

Hastings’ powerful words went alongside flashbacks of the deaths of solicitor Jimmy Lakewell, police officer Lisa Patel, journalist Gail Vella and former Detective Inspector Marcus Thurwell- whom fans believe is still alive.  

Drama: It certainly seems Hastings and his team are on to something as police cars speed down the road, while armed officers close in on a residential area and Hastings briefs his team

Drama: It certainly seems Hastings and his team are on to something as police cars speed down the road, while armed officers close in on a residential area and Hastings briefs his team

Shootout: And it only gets more dramatic as balaclava men jump out of vehicles armed with guns themselves

Shootout: And it only gets more dramatic as balaclava men jump out of vehicles armed with guns themselves

Crime: The police board shows AC-12's work so far; with DI Dot Cottan, Chief Superintendent Derek Hilton, Gill Biggeloe and OCG members including Lisa McQueen and Tommy Hunter

Crime: The police board shows AC-12’s work so far; with DI Dot Cottan, Chief Superintendent Derek Hilton, Gill Biggeloe and OCG members including Lisa McQueen and Tommy Hunter

The trailer then shows acting Superintendent Jo Davidson (Kelly MacDonald) leaving the high-security prison in handcuffs, only to end up alone in a van with a corrupt prison officer who previously injured Lindsay Denton in series three. 

Jo says: ‘What’s going on?’, before the camera flashes a sinister look from the prison officer. 

A handwritten note is also teased in the trailer, with the word definite misspelt to mirror what viewers have seen previously.  

A huge clue of the identity of H began to emerge in series five, when the OCG communicated with ‘H’ through a computer.  

Eagle-eyed fans were quick to notice H spelling definitely as ‘definately’, and this misspelling has been repeated in subsequent episodes. 

Corrupt? Partricia Carmichael will also return after her suspicious behaviour during the interview on the last episode

Corrupt? Partricia Carmichael will also return after her suspicious behaviour during the interview on the last episode 

Will this handwritten report be the breakthrough AC-12 need to close in on ‘the fourth man’?   

It certainly seems Hastings and his team are on to something as police cars sped down the road, with armed officers closing in on a residential area during the trailer. 

The Superintendent briefs DI Kate Fleming, DI Steve Arnott and DC Chloe Bishop as they arrive at the scene.

Hastings says: ‘AFO’s will secure the suspect down’, while the words ‘Every investigation has led to this… H’.   

And it only gets more dramatic as balaclava men jump out of vehicles armed with guns themselves. 

Kate opens the police van, brandishes her gun and shouts: ‘armed police’ before the screen fades to black.   

Action: The snaps, which are thought to be depicting the seventh episode of the series, show a stoney-faced Superintendent Ted Hastings (Adrian Dunbar) getting out his police car

Action: The snaps, which are thought to be depicting the seventh episode of the series, show a stoney-faced Superintendent Ted Hastings (Adrian Dunbar) getting out his police car

Intriguing: Another snap shows Hastings pointedly walking out of the front gates of Decker Avenue Police Station, where Jimmy Lakewell was taken before withdrawing his cooperation with AC-12

Intriguing: Another snap shows Hastings pointedly walking out of the front gates of Decker Avenue Police Station, where Jimmy Lakewell was taken before withdrawing his cooperation with AC-12

The newly-released trailer for the finale showed Kate wearing the same grey turtleneck jumper as she is seen wearing in the on-set snaps, while it teases at the return of the balaclava men and shows DCI Jo Davidson handcuffed in prison.   

Viewers were stunned on Sunday night when it appeared James Nesbitt’s character was killed off before he even appeared on screen – but some are convinced it was a cover-up.

Towards the end of the nail-biting penultimate episode, Guardia Civil police officers stormed Marcus Thurwell’s Spanish home, while the AC-12 team watched via video link.

When the law enforcement officers entered the home, they were met by two bodies, and a Spanish captain turned to the camera and identified one as ‘Senor Thurwell’. 

While many viewers expressed surprise an actor of Nesbitt’s calibre was denied even a scene, some were left convinced Thurwell was in fact the Spanish AFO leading the raid on his home.

Showdown? Other images show Kate (centre) and Steve (right) speak to Hastings, leaving fans asking if the duo confront the AC-12 boss about the £50,000 given to John Corbett's widow Steph

Showdown? Other images show Kate (centre) and Steve (right) speak to Hastings, leaving fans asking if the duo confront the AC-12 boss about the £50,000 given to John Corbett’s widow Steph

Under pressure: Hastings, who has already become exasperated as time is running out before he's forced into retirement and AC-12 is disbanded, is seen looking concerned in the images

Under pressure: Hastings, who has already become exasperated as time is running out before he’s forced into retirement and AC-12 is disbanded, is seen looking concerned in the images

One tweeted: ‘Is it just me or was one of those Spanish “police officers” Thurwell? I’m sure it was him.’

Another wrote: ‘Exactly what I was thinking? Nice job if James Nesbitt only got paid for a few photos so I suspect that Marcus Thurwell is 100% alive.’

And one commented: ‘Is this Marcus Thurwell or have they just found the Spanish Jimmy Nesbitt to play the part?’ – sharing a series of screenshots to illustrate the likeness.

AC-12 were looking into the retired former detective chief inspector after SI Steve Arnott (Martin Compston) learned that Gail Vella – the journalist who was murdered – had been looking into the death of Lawrence Christopher while in police custody – a case Thurwell was in charge of.

Ready to go: Hastings, who is up against the clock before AC-12 is disbanded, is also seen getting out of a police car as things heat up during the series

Ready to go: Hastings, who is up against the clock before AC-12 is disbanded, is also seen getting out of a police car as things heat up during the series

Link: A dramatic trailer for the BBC drama's finale showed Kate wearing the same grey turtleneck jumper as she is seen wearing in the on-set snaps (pictured)

Link: A dramatic trailer for the BBC drama’s finale showed Kate wearing the same grey turtleneck jumper as she is seen wearing in the on-set snaps (pictured)

Thurwell also has links to Darren Hunter, the son of former organised crime group boss Tommy Hunter.

The OCG also murdered Oliver Stephens-Lloyd before he had an opportunity to give evidence about sexual abuse at Sands View Boys’ Home, with Superintendent Ted Hastings convinced Thurwell is connected to the killing and the abuse cover-up. 

When Thurwell was found ‘dead’, Hastings was visibly exasperated – with time running out for him to solve the mystery before his impending retirement. 

Elsewhere in the episode, viewers learned PC Ryan Pilkington met a grizzly end, after working as an inside man in the Murder Investigation Team (MIT) for the Organised Crime Group (OCG). 

Trouble ahead? The images have left people questioning whether Kate (above) and Steve are going to confront Hastings about the mysterious wad of cash given to Steph

Curious: The images have left people wondering what the trio (above, Vicky McClure on set) are doing at Decker Avenue Police Station

Trouble ahead? The images have left people questioning whether Kate and Steve are going to confront Hastings about the mysterious wad of cash given to Steph, and wondering what the trio are doing at Decker Avenue Police Station

Determined: In snaps taken on set, Hastings appeared to be hard at work ahead of his forced retirement as he was seen getting out of a police car looking determined

Determined: In snaps taken on set, Hastings appeared to be hard at work ahead of his forced retirement as he was seen getting out of a police car looking determined 

After being lured to a lonely car park by DCI Jo Davidson during the previous episode, Kate was met by armed officer Ryan who said he planned to kill her as he held up his gun and aimed it at her.

The episode ended as two gun shots sounded, before the new episode revealed that Ryan had been shot twice in the chest, with Kate and Jo fleeing the scene in a Thelma and Louise-inspired fashion.

When DI Steve Arnott arrived with the AC-12 unit they discovered that Kate and Jo had gone on the run and Ryan was dead. 

DCS Patricia Carmichael could be heard telling officers that the duo were considered to be ‘armed and dangerous’ and sent out an order for their address.

Theory: Fans were stunned on Sunday night when it appeared James Nesbitt's character was killed off before he even appeared on screen - but some are convinced it was a cover-up

Theory: Fans were stunned on Sunday night when it appeared James Nesbitt’s character was killed off before he even appeared on screen – but some are convinced it was a cover-up

Some fans believe the Spanish captain was Thurwell in disguise

Towards the end of the nail-biting penultimate episode, Guardia Civil police officers stormed Marcus Thurwell's Spanish home, while the AC-12 team watched via video link. They found Thurwell's body

Towards the end of the penultimate episode, Guardia Civil police officers stormed Marcus Thurwell’s Spanish home, while the AC-12 team watched via video link. They found Thurwell’s body (right) – but some fans believe the Spanish captain was Thurwell in disguise (left)

Despite the gripping hunt for Jo and Kate which commenced, fans were overjoyed that one of their favourite characters had survived.

Elsewhere during the new episode, fans were left convinced that Detective Chief Superintendent Patricia Carmichael is the fourth man after Sunday’s episode.

The officer, played by Anna Maxwell Martin, placed herself at the centre of the action as she ordered Kate Fleming to  be arrested following the shootout and then tried to shut down Ted Hastings’ questions during a very intense interview of Jo.

Some viewers even theorised that Carmichael was trying to send a message during the ‘puzzling’ interview – which also saw Jo discover her paternity despite offering more ‘no comments’ than answers – based on how often she tapped her pen.

This Morse code theory popped up during Arnott’s questioning of Davidson, specifically when he tried to get information about Gail Vella’s laptop and computer.   

Although Davidson remained tight-lipped, Carmichael did seem to start sweating a little as she tapped her pen four times and took a sip of water.

Interesting: While many viewers expressed surprise that an actor of Nesbitt's calibre was denied even a scene, some were left convinced that Thurwell was in fact the Spanish AFO

Interesting: While many viewers expressed surprise that an actor of Nesbitt’s calibre was denied even a scene, some were left convinced that Thurwell was in fact the Spanish AFO

She's alive! Line Of Duty ended on a tense cliffhanger last week after gunshots were fired as DI Kate Fleming and bent copper Ryan Pilkington held up their weapons

She’s alive! Line Of Duty ended on a tense cliffhanger last week after gunshots were fired as DI Kate Fleming and bent copper Ryan Pilkington held up their weapons

Cliffhanger: After being lured to a lonely car park by DCI Jo Davidson (pictured) [Kelly MacDonald] during the previous episode, Kate [Vicky McClure] was met by armed officer Ryan

Cliffhanger: After being lured to a lonely car park by DCI Jo Davidson (pictured) [Kelly MacDonald] during the previous episode, Kate [Vicky McClure] was met by armed officer Ryan

Man down: The episode ended as two gun shots sounded, before the new episode revealed that Ryan had been shot twice in the chest

Man down: The episode ended as two gun shots sounded, before the new episode revealed that Ryan had been shot twice in the chest 

Morse Code is an alphabet that spells out words or messages using a series of short and long sounds, with the officer appearing to make four taps and spell out H.

Carmichael again set alarm bells ringing when she cut off Hastings at the end of the interview following his knockout question about Osborne being H.

Cutting off the AC-12 head’s question, she declared that Davidson was being charged with ‘perverting course of justice and misfeasance in public office’.

The Line Of Duty series six finale airs on BBC One on Sunday at 9pm.

Could it be? Line of Duty fans were left convinced that Detective Chief Superintendent Patricia Carmichael is the fourth man after Sunday's episode

Could it be? Line of Duty fans were left convinced that Detective Chief Superintendent Patricia Carmichael is the fourth man after Sunday’s episode

Trying to hide something? The officer, played by Anna Maxwell Martin, tried to shut down Ted Hastings' questions during a very intense interview of Jo Davidson

Trying to hide something? The officer, played by Anna Maxwell Martin, tried to shut down Ted Hastings’ questions during a very intense interview of Jo Davidson

LINE OF DUTY SEASON SIX: WHAT ARE THE MAIN FAN THEORIES?

Season six of Line Of Duty has left fans with more questions than answers, with viewers flocking to Twitter to question what exactly is DCI Jo Davidson is up to, whether Kate Fleming has really left AC-12 and who is H?

Here, MailOnline examines some of the most prominent fan theories  

Kate Fleming HASN’T left AC-12 and is working undercover   

One of the most shocking discoveries was AC-12’s Kate is now working with a new team- with some fans suggesting she could even be the infamous H.

While chatting to her new gaffer DCI Davidson, Kate said: ‘I got fed upon nicking coppers, I’d rather go after the psycho who murdered Gail [Vella].’

But despite seeming confident in her new role, some viewers were left wondering if all was at it seems and theorised that Kate could still be undercover for AC-12.

Even after she tipped off Davidson and incurred the wrath of Ted Hastings, fans have continued to speculate that she is so deep undercover that even Hastings is having to keep her true agenda secret.  

Kate Fleming HASN'T left AC-12 and is working undercover: Is it true? The jury is still out on this one

Kate Fleming HASN’T left AC-12 and is working undercover: Is it true? The jury is still out on this one 

DCI Jo Davidson is being blackmailed by an Organised Crime Group  

Jo has already survived a grilling from AC-12’s top team and appeared to clear her name when it was ex-girlfriend PS Farida Jatri who seemed to have taken part in corruption.

However, Jo was seen hitching a ride with known bent copper Ryan Pilkington and taken to collect a burner phone, making her look suspicious once more.

Fans, however, are convinced the DCI is being blackmailed by an OCG, following her emotional outburst when she was summoned to pick up a new burner.

DCI Jo Davidson is being blackmailed by an Organised Crime Group: Is it true? After her car park outburst it seems increasingly likely

DCI Jo Davidson is being blackmailed by an Organised Crime Group: Is it true? After her car park outburst it seems increasingly likely

DCI Jo Davidson’s mother is Anne-Marie McGillis

Fans speculated over who Jo’s mother could be after she was seen in a photograph in the first episode.

Many theorised her mother has something to do with season five character John Corbett’s [Stephen Graham] mother Anne-Marie McGillis, who was killed by an Irish Republican paramilitary group sometime after 1989.

DCI Jo Davidson's mother is Anne-Marie McGillis: Is it true? There simply isn't enough evidence yet to determine on way or the other

DCI Jo Davidson’s mother is Anne-Marie McGillis: Is it true? There simply isn’t enough evidence yet to determine on way or the other  

Gail Vella is still alive

Although season six has centered around the murder of journalist Gail Vella, one obscure theory is that she is in fact still alive.  

Craig Parkinson, who played Matthew ‘Dot’ Cottan in the show, said on BBC Sounds podcast Obsessed with Line of Duty: ‘Somebody is in that flat and there’s some connection with Gail Vella, the investigative journalist.

‘You don’t cast someone like Andi Osho and then just have her as little magazine prints and stick them up on a kitchen wall.’

Sarah Millican – who also appeared on the podcast – went on to suggest Vella may have been a former lover of DCI Davidson’s.

Gail Vella is still alive: Is it true? It seems unlikely that the scale of police corruption is so huge that they could fake a murder victim

Gail Vella is still alive: Is it true? It seems unlikely that the scale of police corruption is so huge that they could fake a murder victim

DC Chloe Bishop is Tony Gates’ daughter

Bishop is one of AC-12’s newest recruits, and as Gates and his wife Jools had two daughters, Natalie and Chloe, viewers have suggested their shared first name ‘can’t be a coincidence’.

Gates’ daughter was last seen in season one in 2012, which means she’d be roughly the same age as Bishop is now.

Fans have suggested that Bishop either took her mother’s maiden name or the name of a step-father, so that her true identity remains a secret – for now.

Gates died at the end of the first season when he walked into a busy road after getting a confession from gang leader Tommy Hunter, who had been blackmailing the police officer into covering up their criminal activity.

DC Chloe Bishop is Tony Gates' daughter: Is it true? The dates and facts line up, but there still isn't enough to write it off as a coincidence just yet

DC Chloe Bishop is Tony Gates’ daughter: Is it true? The dates and facts line up, but there still isn’t enough to write it off as a coincidence just yet 

DCI Jo Davidson’s mystery blood relative is…?

After it was revealed that Jo’s DNA matched someone on the Police National Computer, fans theorized who that could be.

The overriding theories suggested that Davidson’s relative was either Tommy Hunter, of series one and two, Mike Dryden of series two, John Corbett of series five, or Derek Hilton, killed off in series four.

Tommy Hunter was the leader of the OCG in earlier series of the show, and a paedophile. His character is dead.

Mike Dryden, the former Deputy Chief Constable, was last seen resigning from his post for perverting the course of justice in series two. His Scottish links also suggest he could be related to Davidson.

John Corbett was an undercover cop in series five who had his throat slit, leaving behind a wife, two daughters, and a mysterious link to a woman, Anne-Marie, whom fans claim could also be Davidson’s mother.

Derek Hilton was a Chief Superintendent and later the Assistant Chief Constable of Central Police. He was also secretly affiliated with organised crime. He was shot in the mouth in a staged suicide in season four.

Other suggestions were Gill Biggeloe, Jackie Laverty, Lindsay Denton or Terry Boyle. 

After it was revealed that Jo's DNA matched someone on the Police National Computer, fans theorized who that could be. Scottish Mike Dryden was last seen resigning from his post for perverting the course of justice in series two

After it was revealed that Jo’s DNA matched someone on the Police National Computer, fans theorized who that could be. Scottish Mike Dryden was last seen resigning from his post for perverting the course of justice in series two

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