Line of Duty season six - final episode air date, cast, plot, trailer, H theories and what's happened so far

Line of Duty Season 6
(Image credit: BBC/World Productions/Steffan Hill/Geraint Williams)

Line of Duty season six - everything you need to know about the current series...

Line of Duty season six has brought AC-12’s finest - Ted Hastings (Adrian Dunbar), DI Kate Fleming (Vicky McClure) and DS Steve Arnott (Martin Compston) back to our screens for a new case.

Written again by Jed Mercurio, season six also features Trainspotting and Harry Potter star Kelly Macdonald.

When does Line of Duty season six air — Line of Duty series 6 final episode air date confirmed

Line of Duty season six started on Sunday, March 21st and airs on Sunday nights on BBC One at 9pm. The Line of Duty series 6 final episode air date is Sunday 2 May on BBC1 at 9pm.

There is seven episodes, making it the longest series to date.

You can catch up on missed season 6 episodes on BBC iPlayer now as well as refresh your memory on seasons 1-5.

Line of Duty series six filming restarting

The cast and crew working on series six of Line of Duty (Picture: BBC)

What’s the plot?

Each of the first five series of Line of Duty sees the story revolving around one central character the team are investigating. As fans will already know, the pivotal character this time is DCI Joanne Davidson, played by Kelly Macdonald. She heads up the Murder Investigations Team (MIT) at Hillside Lane station, who are conducting an investigation into the murder of Gail Vella.

AC-12 are also trying to work out who's behind the murder, and whether Jo is involved. MIT is currently trying to pin Gail's murder on Terry Boyle, a character who we know has been used by the OCG several times already. This is the most explosive season yet, but we should expect even more action from the last few episodes!

Will Jo be behind her murder after all? Is she truly a bent copper? We still can't be sure...

What happened in season 6, episode one?

Warning - spoilers for the first episode below

Probably the biggest shock in the opening episode of season 6 was the fact Kate is no longer on the AC-12 team. She is now working directly under newcomer DCI Jo Davidson as they try to crack the murder case of journalist Gail Vella.

We have also learned that Steve isn't happy with his role on AC-12 and is looking to try something new within the police force... plus he also seems to be battling a painkiller addiction judging by his stash of tablets at home.

Joanne Davidson seems to be hiding some serious skeletons in her closet, not only is she now under suspicion after a questionable decision to reroute the Terry Boyle arrest by suggesting they investigate an armed robbery, but she was also in a doomed relationship with fellow police officer, Farida Jatri.

The CHIS (Covert Human Intelligence Sources to you and me!) who gave the name Ross Turner to the police is also dead, but did he jump or was he pushed? Did DCI Davidson have something to do with his death?

And Terry Boyle from seasons 1 and 5 is also back, this time under suspicion for killing Gail Vella. But what is his connection to the OCG these days? And where has his fridge freezer gone?!

TV tonight Line of Duty

Steve hashes out the case against Jo to Ted early on.

What happened in episode two?

If you're not caught up, don't read on!

In episode two, Ted finally authorises AC-12 to start investigating MIT. Scared for her life, Farida requests a transfer to another police department, away from Jo.

Meanwhile, Steve finds out that Gail Vella might have uncovered something crucial to exposing police corruption, but her back-ups have been stolen!

The Hill is rocked by the news that Carl Banks has been found dead at an abandoned site. A new officer, Ryan Pilkington, finds a knife at the scene that ties Alistair Oldroyd, aka "the CHIS", to the murder. Kate seems sure that she recognises him from somewhere.

Steve informs Kate that AC-12 are moving ahead with their investigation, and she betrays his trust by revealing this to Jo. This allows her to prepare for their arrival and withhold evidence due to her "concerns" about info being leaked to the OCG.

This doesn't stop AC-12 though, and they turn up again later on to start seizing computers and files relating to Operation Lighthouse. Whilst there, they even serve a very smug Jo with a Regulation-15 notice for gross misconduct!

Ted, Steve and Chloe grill Jo in a tense interview, where she throws suspicion at Farida, urging them to search Farida's home just before AC-12 place Jo under arrest. A forensic team then uncovers a stash of burner phones hidden in Farida's home, leading to Farida's arrest and forcing AC-12 to let Jo go free once more.

Ryan is waiting to drive her home, but he takes her to a shady underpass. There, she receives a parcel containing yet another mobile phone, proving that she's a bent copper!

TV tonight Line of Duty

Jo was finally revealed to be a bent copper after all!

What about episode 3? What's Jo up to?!

MASSIVE spoilers ahead!!

Episode three finally saw Kate working more closely with AC-12 once again!

At the start of the episode, DS Chris Lomax informs Jo that he's found a new witness who saws she saw Terry Boyle arguing with the CHIS, Alistair Oldroyd. Terry is brought back to the Hill and interviewed once again. Just as Terry's about to reveal some new info, Jo ends the interview out of concern for Terry's mental wellbeing.

Ryan joins Terry as he is escorted home, reminding him he's still his "best mate". Ryan tells the driver, PC Lisa Patel, the route has changed, directing her to drive by a reservoir. Out of nowhere, he attempts to strangle her, sending the car into the water! Against all odds, Lisa, Terry and Ryan survive, so Ryan returns to the reservoir and drowns Lisa in the water. Luckily, Kate had spotted the car change course and followed it to the water, arriving just in time to stop Ryan from killing Terry, too.

Steve finally reveals Ryan's true identity to Kate. He's also scared by the sudden arrival of AC-9 officers who have been asked to attend and conduct routine drugs tests of AC-12 officers. Ted told them Steve wasn't available, but he clearly knows Steve is in a bad place...

Steve goes to confront Steph Corbett now he knows Steph told Ted about his drug addiction (although he later spends the night with her!). Meanwhile, Ted is told to end the search for H by DCC Andrea Wise!

Back at the Hill, Kate interviews Ryan, fully aware he must be working with the OCG. Farida refuses to give AC-12 a second interview after her wrist is broken by a prison guard.

Later on, Jo confides to Kate that she believes DSU Ian Buckells is the one leaking info to the OCG, and the missing Gail Vella documents turn up in the boot of his service vehicle, and he is brought into AC-12 for questioning. At the end of the episode, Jo tells a mystery contact that it’s “all okay” with Buckells as her scapegoat.

TV tonight Line of Duty

Ted Hastings got his final warning to end the search for H in episode 3.

What happened in episode 4?

HUGE spoilers ahead for episode 4!

Jo Davidson is made a temporary SIO after Buckells’ arrest. Ted and Kate meet to discuss what to do about Ryan Pilkington at the underpass, but Kate suggests just placing him under surveillance to avoid alerting him.

Steve, Chloe and Ted interview Ian Buckells about his role in Operation Lighthouse. Steve believes Buckells is too incompetent to be working for the OCG, but Kate believes this is just his cover. Meanwhile, Ted is informed by DCC Andrea Wise that he’s no longer able to lead his department and encouraged to “retire”.  AC-12 will be merged with AC-3 and AC-9 into a brand new unit, with a new commanding officer. 

Elsewhere, Jo attempts to distance herself from the OCG and tries to transfer Ryan to a different department. Kate’s surveillance reveals Ryan has been stalking and watching Jo, and he intimidates her into keeping him at Hillside Lane to continue working for the OCG. 

Later on, Steve identifies Jimmy Lakewell’s voice from one of Gail Vella’s unreleased podcast files. Steve arranges an offer of immunity and witness protection in exchange for new information on the OCG. Later, officers attempt to remove Jimmy from HMP Blackthorn, but the OCG ambush the police convoy en route, leading to an incredibly tense shoot out!

Buckells is sent to Blackthorn, and Lee Banks uses him to distract Jimmy just long enough to so he can murder Jimmy for being a “rat”. DNA traces at Farida Jatri’s home suggest Jo may have planted the burner frames to frame her. The same traces are also checked against officer data, and they reveal she is related to someone who already appears in police databases… but who could it be?!


Line of Duty series six

Steve pulls off a daring shot during the OCG hijack.

What happened in episode 5?

HUGE spoilers for episode five below!

Thanks to a tip-off from Jimmy Lakewell before his murder, Steve and Chloe begin digging into the death of Lawrence Christopher. Kate tells AC-12 that Jo is giving her the cold shoulder. In an effort to convince Kate that Jo’s a bent copper, Ted and Steve reveal Jo is related to none other than Tommy Hunter, the main criminal from season one!

At Hillside Lane, Kate leads an operation looking for the OCG's untraceable firearms workshops at three local industrial estates, but orders all MIT officers to surrender their phones to stop potential leaks to the OCG. Unknown to MIT, AC-12 officers are lying in wait at each site, and they catch Ryan on camera leaking info about the operation using a concealed burner phone.

Chloe goes over the inquiry into the mishandling of Lawrence Christopher’s case, and finds the former SIO Marcus Thurwell is also connected to the Sands View case from season three! Steve and Chloe continue to investigate why Thurwell could be connected to Gail Vella’s murder, leading them to pursue a new interview with disgraced Chief Superintendent, Patrick Fairbank.

Later, AC-3’s DCS Patricia Carmichael, who’s lined up as Ted’s replacement at the new anti-corruption unit, begins interfering with the investigation into Operation Lighthouse. She tells him to let Buckells go, and suspends all AC-12's ongoing surveillance ops on Terry Boyle, Ryan Pilkington and Jo Davidson!

Meanwhile, Jo lures Kate out to a lorry park after her OCG contact tells her she has to get rid of her fellow officer. There, Ryan emerges, entering into a tense stand-off with Kate. The episode finishes with the sound of two gunshots...but who shot who?!

Line Of Duty - Ep 5

Steve at the raid on the OCG firearms workshop at White Rock Park.

What happens in episode six?

In the sixth episode of season 6, AC-12 find Ryan Pilkington’s corpse at the lorry park, but Kate and Joe have fled the scene. Kate takes Jo with her to grab Steve's car so they can go on the run. DCS Carmichael orders their arrest and tells Chloe to stop the investigation into Chief Constable Philip Osbourne. 

Despite Kate's slick driving, police track her and Jo down very quickly. We later learn Carmichael was authorised to have trackers placed on all AC-12 vehicles by the Chief Constable. Carmichael assumes authority over the case against Jo Davidson.

Jo is initially uncooperative in her interview, but after AC-12 reveal their forensics make Tommy Hunter both her uncle and father, she starts opening up and confessing what she's done to delay the Gail Vella inquiry. Ted tries to push Jo to give up crucial info on the Fourth Man (aka H), but DCS Carmichael continues to shut him down, calling his questions irrelevant. Jo denies any knowledge of Gail Vella’s interest in the Lawrence Christopher case but refuses to say whether she knows Marcus Thurwell or not.

Carmichael shuts down Ted once again after she tries to claim she shot Ryan, not Kate, and she concludes the interview whilst before Jo can reveal who runs the OCG. Carmichael charges Jo with perverting the course of justice and malfeasance (wrongdoing) in a public office. 

After Jo’s interview, we learn Steve’s now just five days from suspension for ignoring all those emails from Occupational Health and Ted’s at rock bottom over AC-12’s imminent closure, and Carmichael's interference with their investigation into police corruption. 

Steve and Kate meet outside of work to discuss how to close their cases. They go to meet Chris Lomax at the OCG firearms workshop, where forensics have found evidence linking the workshop to the firearms used in the Jimmy Lakewell ambush. Kate's now the senior officer on Operation Lighthouse, and she orders the floor dug up. 

Steve and Kate get called back to AC-12 as Spanish authorities have located Marcus Thurwell. The Spanish officers raid Thurwell's home, but they find two dead bodies inside. Meanwhile, Jo is put in prison, where the two bent prison officers who assaulted Lindsay Denton try to approach her, but they back off after spotting the CCTV cameras outside her cell. Will they get to her before AC-12 close the case? 

Jo Davidson

Episode six is mostly focused on Jo Davidson's interview.

What happened in episode seven?

MASSIVE spoiler ahead for episode seven!

A strongbox is uncovered underneath the floor of the OCG workshop. It contains the missing evidence that finally connects Carl Banks to Gail Vella’s murder and the murder weapons from Maneet Bindra, John Corbett and Jackie Laverty’s deaths, too.

Chloe turns up cybercrime evidence that suggests Marcus Thurwell was a decoy the entire time. The cybercrime unit then intercepts a text that instructs OCG officers to retrieve Jo from HMP Brentiss. Since it contains the infamous misspelling of “definately”, Ted organises a hasty interception of the prison transfer vehicle.

With Jo back in safe hands, AC-12 press her to give up the fourth man. She points to Patrick Fairbank as the mystery police officer she was led to fear, but he proves unhelpful in another interrogation. Whilst AC-12 continue to find nothing, Chloe gets to work with cybercrime. By searching past police reports for the word “definately”, they finally identify the real fourth man, who had been hiding in plain sight all along!

After Steve and Kate confront Ted about the money he gave to Steph Corbett and leaking the existence of an informant to Lee Banks, armed officers bring in Ian Buckells for a tense interrogation about his activities as the fourth man! His cover had been his incompetence all these years!

After Buckells’ arrest, Kate and Steve reconcile at the pub and Ted tells DCS Carmichael that he’s lodged an appeal against his enforced retirement. Carmichael tells him that historic corruption cases will not be a priority for investigation, prompting Ted to make a statement about his involvement in the information leak that led to John Corbett’s death.

In the epilogue, we learn that both Terry Boyle and Farida Jatri have been cleared of any criminal charges, and Jo has been placed under witness protection. Darren Hunter (Tommy Hunter’s son) is to be investigated for Lawrence Christopher’s murder, and Ian Buckells has been placed in a maximum-security prison.

The planned restructure of anti-corruption is still to go ahead, and we’re told that AC-12’s powers to curb wrongdoing in public office “have never been weaker”... Is this really be the end AC-12?! 

Kate, Steve and Ted in Line of Duty season 6 episode 7

Kate, Steve and Ted looking over evidence of Ian Buckells' criminal activity.

Who was H?

Finally, we got to find out who H was!

We'd spent years pouring over clues trying to figure out who H is ever since DI Cottan first signalled via morse code that there were four "Hs"!

After Cottan, ACC Derek Hilton and Senio Legal Counsel Gill Biggeloe were unmasked, we learned at the end of season 6 that the so-called "Fourth Man" was none other than DSU Ian Buckells!

Who’s in the cast?

Line of Duty season 6 take one

The very first take of the new series (Picture: BBC)

Alongside the regular cast and Kelly Macdonald, newcomers Shalom Brune-Franklin (Our Girl), Perry Fitzpatrick (Downton Abbey), Andi Osho (I May Destroy You) and Prasanna Puwanarajah (Doctor Foster) have also joined the series.

Shalom Brune-Franklin plays DC Chloe Bishop, a new AC-12 recruit who has been brought in to help crack down on Davidson.

Line of Duty season six lead cast

Kelly Macdonald plays a key part in the new series (Picture: BBC)

Who is Gail Vella?

Gail Vella Line of Duty

Gail Vella is the series six murder victim (Picture: BBC)

Gail Vella is an investigative TV journalist who was shot dead outside her house in the Kingsgate area on 10th September 2019 at point blank range.

It has been suggested by the investigating team that she was either the target of a contract killing, or that she was murdered in cold blood by a crazed fan or stalker.

Gail’s high-profile and yet unsolved murder is now being worked on under the investigation name Operation Lighthouse, which is being led by newcomer DCI Joanne Davidson and has none other than a certain Kate Fleming on the team.

Is there a trailer?

Yes - and it's a good one!

What else do we know?

Series six is filmed in Belfast and production was forced to be shut down due to the pandemic last spring.

Thankfully the team worked against the odds and got the rest of the series filmed after lockdown one restrictions eased.

Line of Duty series 6 airs on Sundays at 9pm on BBC One – see our TV guide for more shows to enjoy. You can catch up on series 1-5 on BBC iPlayer now.

David Hollingsworth

David is the What To Watch Editor and has over 20 years of experience in television journalism. He is currently writing about the latest television and film news for What To Watch.

Before working for What To Watch, David spent many years working for TV Times magazine, interviewing some of television's most famous stars including Hollywood actor Kiefer Sutherland, singer Lionel Richie and wildlife legend Sir David Attenborough. 

David started out as a writer for TV Times before becoming the title's deputy features editor and then features editor. During his time on TV Times, David also helped run the annual TV Times Awards. David is a huge Death in Paradise fan, although he's still failed to solve a case before the show's detective! He also loves James Bond and controversially thinks that Timothy Dalton was an excellent 007.

Other than watching and writing about telly, David loves playing cricket, going to the cinema, trying to improve his tennis and chasing about after his kids!