*Warning: Line of Duty spoilers*


It's been quite the series of Line of Duty, with every single episode seeming to ramp up the tension a further few notches.

With just two episodes to go, we're now firmly at the business end of the season, but there are still plenty of loose ends to tie up – not least the fallout from the incredible cliffhanger at the end of episode five.

We've still got a lot to learn about DCI Joanne Davidson (Kelly Macdonald) and how exactly she fits into the OCG plot, while this season has also seen a glut of returning characters from series gone by, with the likes of Jimmy Lakewell, Patrick Fairbank and Philip Osborne.

And last week also saw the return of Ted Hasting's nemesis in the shape of AC-3 chief Patricia Carmichael (Anna Maxwell Martin) while also briefly introducing a new character played by James Nesbitt – named Marcus Thurwell.

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If you're still processing everything that happened in the last episode, check out our round-up of the biggest Line of Duty questions and theories after episode five, which should serve as a handy refresher before diving into the next instalment.

Here's what we know so far about the Line of Duty cast, air date, and plot of series six.

Line of Duty series 6 air date: When is it on?

Line of Duty series six premiered on BBC One on Sunday 21st March at 9pm.

The show will continue to drop new episodes every Sunday over the next six weeks, before concluding with its seventh episode on Sunday 9th May.

How many episodes are there in Line of Duty series 6?

There will be seven episodes! The show was originally commissioned for six hour-long episodes, but in February 2021 it was announced that Line of Duty fans were getting an extra helping.

A press release said: "AC-12’s highest priority will always be capturing bent coppers. With that in mind, we have requested and been granted an extension of an extra episode for our next series, making it our longest yet."

We also got this video, straight from the officers of AC-12 themselves:

Line of Duty series 6 cast: Who stars in Line of Duty?

Line of Duty series 6 stars Shalom Brune-Franklin
Line of Duty series 6 stars Shalom Brune-Franklin BBC

Line of Duty's three lead actors, Adrian Dunbar (Supt Ted Hastings), Vicky McClure (DI Kate Fleming), and Martin Compston (DS Steve Arnott), are all back for series six to the delight of fans.

Joining them is Shalom Brune-Franklin as DC Chloe Bishop – the newest member of the AC-12 team. The actress has previously starred in Cursed, Our Girl, Bad Mothers, and Our Girl.

Another new cast member for series six is actress and comedian Andi Osho, playing a journalist named Gail Vella, who is believed to have been murdered. You may recognise her from I May Destroy You, Curfew, or Kiri.

Prasanna Puwanarajah (of Defending the Guilty, Patrick Melrose, Doctor Foster, and World on Fire fame) also joined the cast, as Perry Fitzpatrick – who previously starred alongside Vicky McClure in Channel 4’s This Is England and I Am Nicola.

Line of Duty - series 6 new cast
Line of Duty - series 6 new cast Don Arnold/WireImage/Michael Tullberg/David M. Benett/Getty Images

It’s also possible that Taj Atwal (PC Tatleen Sohota) and Aiysha Hart (Murder Squad cop DS Sam Railston) will make a comeback.

Polly Walker's character Gill Biggeloe has been given a new identity, which doesn't entirely rule out a return in season six, but there would have to be some sturdy justification for bringing her back.

The guest lead for series six of Line of Duty is Kelly Macdonald, who plays DCI Joanne Davidson, "the senior investigating officer of an unsolved murder, whose unconventional conduct raises suspicions at AC-12".

Kelly Macdonald

Line of Duty writer and showrunner Jed Mercurio said at the time of her casting: "We're honoured that Kelly Macdonald will join Martin, Vicky and Adrian in series six of Line Of Duty. DCI Joanne Davidson will prove the most enigmatic adversary AC-12 have ever faced."

In recent years Macdonald has starred in The Victim and Giri/Haji. She is also known for her roles in Trainspotting, Gosford Park, State Of Play, No Country For Old Men and Boardwalk Empire.

And interestingly, Macdonald revealed that she had to think twice about accepting the role, only being persuaded to take it after advice from former Line of Duty guest star Keeley Hawes, who played Lindsey Denton in series two and three.

Vicky McClure and Kelly Macdonald in Line of Duty
Vicky McClure and Kelly Macdonald in Line of Duty (BBC)

“The real issue was the sheer number of words I had to learn,” she told Radio Times. “When I saw the script, my first instinct was to run a mile. It’s all addresses and dates and police jargon, especially when I was interviewing suspects.

"Keeley was brilliant; she talked me down from the ledge. She said it might look as though you are being asked to do something completely impossible, but it’s not.”

We got our first look at DCI Joanne Davidson, sitting across the table from AC-12 in the interview room before "battle commences" and an interrogation begins:

Line of Duty series 6 plot: What will happen?

Not even an intense AC-12 interrogation could get the Line of Duty team to give away any spoilers, but we do know a few things.

Season six will feature a brand new case for AC-12 as they investigate DCI Joanne Davidson (Kelly Macdonald) for her suspicious conduct around the attempted arrest of a murder suspect.

However, things are rather different this time as dynamite duo DI Kate Fleming and DS Steve Arnott have been separated, following the former's transfer to Davidson's squad.

Of course, Fleming has gone undercover before but it appears that this time is a genuine and permanent move, which puts her in a difficult position when Steve begins his investigation.

Things are looking tough for him personally in the series six premiere too, with one particular sequence suggesting he has developed an addiction to painkillers following his serious injury in series four.

Martin Compston previously teased a bombshell at the end of episode four – and he said episode five was "worth the wait". Vicky McClure commented that she'd "been sitting on these incredible scripts for some time now," while Adrian Dunbar would only say: "Even with the imposition of COVID restrictions I can't hide my excitement at getting the team back together. So many people wondering… what happens next?”

(Yes, Mr Dunbar. We are.)

Casting around for further clues about season six, it also looks like it might be set in the dead of winter? Seeing as Vicky McClure's DI Kate Fleming is pictured on set wearing a stripy polo neck and a thick suit jacket. Or does AC-12 just have very intense air conditioning? We can but speculate.

Speaking of which, Jed Mercurio teased on Twitter that he'd hidden a clue in a behind-the-scenes photo of Martin Compston – claiming that the "inmate" opposite Compston had been deliberately hidden in the photo, but that eagle eyed viewers might just about manage to see an out-of-focus image on the camera monitor.

He added: "Clue: it’s not Julia Montague" - a reference to the character played by Keeley Hawes in his other BBC drama Bodyguard. Hawes' own Line of Duty character Lindsay Denton was (spoiler alert!) killed off in series three, but Mercurio certainly enjoys stirring up speculation.

And indeed, he doubled down on that particular clue in a later tweet after the end of BBC One's repeat of series two and just before the new series debuted, writing, "Thanks to everyone who watched the conclusion of #LineofDuty Series 2 @BBCOne last night. There's still time to catch up @BBCiPlayer on Series 3-5 ahead of Series 6 starting next Sunday night. You never know where you might see Lindsay Denton pop up again..."

Similarly, the showrunner teased us with a so-called Line of Duty "cryptic plot clue" from the set of season six, winding up fans with a shot of a building painted with the word "Arnott's". (Steve Arnott – get it?)

And Mercurio again shared some new images in September to tease an impressive stunt that we will see during series six – posting a photo of a van tipped over onto its side and singing the praises of the stunt team involved.

He wrote: "Huge respect to our stunts team led by Donal O’Farrell featuring ace stunt drivers Steph Carey and Dave Anders. It’s easy for me to write ‘van rolls’ – they make it happen.”

He followed that up in October with some shots of the AC-12 trio filming on location in Belfast. And based on Steve Arnott's uniform, fans have been wondering whether they've spotted an important detail: is Arnott no longer a Sergeant?

Of course, part of the fun of Line of Duty is trying to work out exactly what might be going on – and Martin Compston has revealed that he's always surprised how often fan theories tend to be fairly accurate.

Speaking to RadioTimes.com and other press ahead of the series launch, he said, "One of the great joys of the job is these theories that fans come up with.

"And a lot of the time they’re absolutely spot on. Obviously, we can’t ‘like’ or say it to give it away. “But that’s one of the great things – and think that’s one of the reasons why they’re holding the show, it’s one episode a week and giving people time to do their research and all these podcasts and recaps and that kind of thing."

Will this be the final series of Line of Duty?

No firm news just yet – but series seven has yet to be commissioned.

Martin Compston has said he'd like to do one more series, to have a "proper" post-COVID send-off. He revealed that the atmosphere on set "wasn't the same" as it had been while making previous series due to restrictions which made connections with cast and crew difficult,

“It always depends on audience reaction and whether there’s a desire for more," the actor told The Guardian.“We want to leave a good legacy and be remembered as one of the great shows, not for a disappointing final series. But this was a strange one to make, thanks to the horror show we’ve all been living through.

“We had a seven-month filming break, then came back under all the restrictions. The crew had to keep their distance. Masks made it harder to make a connection. The atmosphere on set wasn’t the same.

“It would be tough to end it that way. So on a personal level, it would be nice to do at least one more when life was back to normal and we could have a proper send-off."

"I think as long as there's an appetite from our audience for the show, we'll keep going," Adrian Dunbar said during an appearance on the Graham Norton Radio Show in January. "Why would we stop? We've managed to keep the standard, Jed [Mercurio] rather, has managed to keep the standard so high for so long, and people love the show. I hope it does go on."

He added: "But of course everything is finite, I see Peaky Blinders is coming off after six fabulous seasons. When it ends, it will end, and we'll have all had the most wonderful time."

Mercurio himself told RadioTimes.com in 2017: "Whether I would go beyond six would depend on how series five went... at the moment there is a great appetite among all of us involved in the programme to do more. What we don’t know is whether there will come a point where we kind of lose that enthusiasm to keep going back."

He followed this up in 2019 at the BFI & Radio Times Festival by explaining that he'd have a conversation with the BBC after series five: “Once series five has finished airing we’ll have a conversation with the BBC, with a view to whether there’s a possibility to series seven being commissioned. But we definitely know we’ve got series six." (So has that conversation now happened? If it has, Mercurio hasn't shared the news with anyone.)

Just prior to the season six premiere, Mercurio confirmed that while he was still hoping for a seventh series, no firm plans were in place just yet.

"We’re in a situation where it’s not entirely clear that there will be a seventh series," he told Radio Times. "We would hope there could be. But we’re having to do our planning coming out of COVID, and a whole bunch of other things around the idea that these things aren’t guaranteed at all now.”

He added: “Since probably season four, we’ve been talking to the BBC about the realistic longevity of the series. I’ve experienced broadcasters pulling the plug while we were still developing a storyline –Bodies and Cardiac Arrest both ended prematurely on the BBC. So it’s an ongoing discussion, is all I can say. A lot of it depends on the key creatives – me and the main actors – finding new stories to tell within that universe.”

Judging from series five viewing figures, a recommission seems likely. Its opening episode drew in a peak audience of over eight million viewers, with an average of 7.8 million watching the entire episode — that’s larger than the season four finale in 2017.

Line of Duty series 6 trailer

The first full trailer for the new series arrived on 9th March 2021, and it's safe to say there's rather a lot to unpack in the 70-second clip.

Towards the start of the trailer, Ted Hastings declares that AC-12 are looking into “this force’s highest-profile investigation” and there are plenty of hints that it won't be an easy case, with Steve Arnott declaring "A whole line of enquiry has been deliberately suppressed to protect organised crime."

And some fans reckon the trailer could hint at trouble for Kate Fleming – in the final moments of the trailer, new recruit Chloe asks Steve if he thinks there’s a fourth man out there, to which he replies, “Man, or woman" – before we cut directly to one final shot of Kate.

This being a Line of Duty trailer, that wasn't the end of the clues – some eagle-eyed fans spotted that by scanning a QR code on a magazine cover featured briefly in the trailer, you can unlocks a Line of Duty Easter egg – a letter from Philip Osborne, Chief Constable (Owen Teale) to DCC Andrea Wise (Elizabeth Rider).

And that wasn't all – a link in the PDF letter document leads to another document starting a clue trail that eventually leads to an exciting first look Line of Duty clip from the new series, which shows Steve drop the bombshell that he may be considering leaving AC-12 behind...

Earlier the BBC had released a new teaser that also appeared to show Vicky McClure's Kate in trouble. After what happened to Hastings and Steve in previous series, it is probably her turn to be fair...

And just before the new series debuted in March 2021, several new images of the new series were released, including some showing Martin Compston sporting his new, more bearded look for season 6.

Adrian Dunbar and Martin Compston in Line of Duty season 6

We also got a closer look at Kelly Macdonald as new character Joanne Davidson, who looks to be spending a lot of time in the series with Kate Fleming...

Line of Duty

How did they film Line of Duty during COVID?

Line of Duty was one of the shows that had to suspend filming in March 2020, when the coronavirus pandemic hit. However, the production team managed to kickstart filming again in September, and Line of Duty season six wrapped filming in November 2020.

Martin Compston announced the news on Twitter, writing: "Delighted we've finally wrapped series six! Tip of the cap to the production team for putting the protocols in place to provide a safe working environment and to the phenomenal crew, having the discipline and determination to work within the new parameters and get us over the line."

Filming for Line of Duty season six originally got underway in February 2020, and we had initially been expecting the drama to air in 2020. However, as the coronavirus pandemic escalated, producers made the decision to suspend filming four weeks in to the shoot. Lockdown was officially imposed days later.

Line of Duty series 6 filming pictures
World Productions

In May 2020, creator Jed Mercurio gave an update to fans on The Andrew Marr Show, stating that it was "in doubt" whether Line of Duty would resume filming this year or have to pick back up in 2021. But by June 2020, during an appearance on the A Stab in the Dark podcast, the showrunner was more hopeful.

Several UK broadcasters, including the BBC, announced in July that they would resume TV production with new COVID-19 safety guidance. A major government-backed insurance scheme has also been launched, removing another obstacle to production.

And in August 2020, RadioTimes.com was able to host a livestreamed Q&A with Vicky McClure (DI Kate Fleming), Adrian Dunbar (Superintendent Ted Hastings), Martin Compston (DS Steve Arnott), Lennie James (DCI Tony Gates), Craig Parkinson (DI Dot Cottan), executive producer Simon Heath and showrunner Jed Mercurio.

Heath told RadioTimes.com that production would restart "soon", while Mercurio said: "We'd love to be on air next year, so we really have to make sure we complete our filming before Christmas."

Then, on 1st September 2020, the BBC announced that filming had officially resumed.

Executive producer Simon Heath said in a statement: "It’s been almost six months since we stopped shooting, but following our implementation of all the industry COVID protocols, we’re delighted to be able to resume filming series six safely.”

Mercurio added: We know Line of Duty fans are desperate for series six and we hope we can get it on air as soon as possible. Thanks so much for your patience in these difficult times."

On the question of whether the drama will incorporate the pandemic, Mercurio told RadioTimes.com during a live-streamed Q&A: "We're still talking about it. There are some things that we can do, some very simple things that the audience won't notice, like have as many scenes outdoors as possible, which allows social distancing of the crew, and it's a safer environment for COVID. So we're looking at things like that, which are kind of invisible changes.

"But we would obviously have to think very carefully about doing visible changes."

Martin Compston also had concerns about continuity between footage shot pre-lockdown and post-lockdown, joking: "We'll have to accommodate the stone of weight that I've put on!" – while Mercurio teased a fake plot detail for season six: "Martin has to go undercover and it's part of his disguise, to be a stone heavier."

And appearing on The One Show in August, Martin Compston said: "I think if there's changes that are possible in terms of moving scenes which were indoors, outdoors, where possible – but we really wouldn't want to compromise the scripts."

How to watch Line of Duty online

Line of Duty is available to stream now on BBC iPlayer. Series 1-4 is also available to watch on Netflix (as of 30th June 2020).

If you would prefer to own every episode, you can pick up the first five seasons in one handy DVD box set through Amazon UK.

Line of Duty recap: What happened in series 5?

You can see a summary of each episode here, or read a (spoiler-heavy) synopsis below...

  1. Line of Duty series 5: episode 1
  2. Line of Duty series 5: episode 2
  3. Line of Duty series 5: episode 3
  4. Line of Duty series 5: episode 4
  5. Line of Duty series 5: episode 5
  6. Line of Duty series 5: episode 6

The fifth run of Line of Duty centred on John Corbett (Stephen Graham), a rogue undercover officer who would go to any lengths to catch ‘H’, the corrupt copper at the heart of the Organised Crime Group (OCG).

As the series progressed, we learned that Corbett had links to AC-12 chief Ted Hastings. It transpired that Corbett’s mother, Anne-Marie, was a police informant who had a relationship – professional and perhaps more – with Hastings during The Troubles in Northern Ireland.

Thanks to lawyer Gill Biggeloe – who was secretly in league with the OCG – Corbett believed Hastings was responsible for Anne-Marie’s death at the hands of paramilitary forces. And, again due to Biggeloe, Corbett was determined to prove Hastings was a bent copper.

But his mission was cut short when the OCG discovered Corbett was a rat and slit his throat.

Line Of Duty S5 - Episode 1

How did the OCG find out Corbett’s true identity? By the end of the series, it still wasn’t clear. According to OCG member Lisa McQueen, Corbett’s cover was blown thanks to a tip-off from Lee Banks, an imprisoned henchman from the same gang.

And where did Banks get this information from? Although never proven, many suspected Ted Hastings was the source. As AC-3 leader DCS Patricia Carmichael (Anna Maxwell Martin) theorised, Hastings could have leaked this intel as revenge – earlier in the series Corbett had beaten Ted’s wife.

After a large amount of bribe money was discovered in Hastings’ shabby hotel room, Carmichael then arrested him for conspiring to murder Corbett. And, going further, she intended to prove Hastings was ‘H’. However, this investigation only revealed that Biggeloe was actually trying to frame Ted for everything.

But although Hastings returned to active duty at the end of the series, he’s sadly not completely off the hook just yet…

Series six has been confirmed as taking place 18 months on from the events of the previous series.

Who is H?

Not one person, but four. Turns out that AC-12 had misinterpreted the dying testimony of Dot ‘The Caddy’ Cottan: instead of one police Kingpin called ‘H’, there’s actually a quartet of high-ranking police staff working with the OCG.

Looking back at the testimony, Steve Arnott and Kate Fleming noticed that Craig Parkinson’s character was tapping out the Morse code for ‘H’ on his left hand. Combining this signal with Cottan blinking at the letter ‘H’, the AC-12 detectives deduced he wasn’t trying to reveal the identity of one bent copper, but make it clear there’s four in the service.

Dot's dying declaration

In other words, there are four corrupt officers – and they’re not necessarily called ‘H’.

How much does this revelation change Line of Duty? At this stage in the show, not a lot. After all, as Fleming outlines, AC-12 has already discovered three of the four ‘H’s (again, just to clarify, their name doesn’t have to start with ‘H’). And they are…

  • DI Matthew Dot Cottan – as known as ‘The Caddy’
  • Lawyer Gill Biggeloe
  • Chief Superintendent Derek Hilton

There’s still one out there, though. As before, AC-12 are on the hunt for one corrupt senior member of the service.

The bad news? It could be anyone – their name doesn’t have to start with ‘H’. The good news? The final ‘H’ maybe isn’t as powerful as was feared – they were just one of four, not a single criminal mastermind.

Where is Line of Duty filmed?

Line of Duty is filmed in Belfast, where the cast relocate during shooting. Series six saw Martin Compston, Vicky McClure and Adrian Dunbar return to the Northern Irish capital, but the cast and crew were released when filming was halted due to coronavirus.

They returned to Belfast to continue filming later in the year, and wrapped production in November 2020.

Line of Duty airs on BBC One on Sundays at 9pm. If you caught the first instalment of season 6, you can read our Line of Duty episode 1 recap, or if you need a broader refresh you can read our Line of Duty recap of everything that has happened before season 6. If you want to rewatch these previous seasons, you can also buy the Line of Duty boxsets on Amazon now.


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