Line of Duty series 6: Everything we know, from BBC release date, new cast members to ‘H’ theories

New series will feature ‘the most enigmatic adversary AC-12 have ever faced’

Over the past eight years, Line of Duty has evolved from a small BBC Two drama to BBC One’s biggest ratings-puller.

The series, from Bodyguard creator Jed Mercurio, follows AC-12, a fictional police squad assigned with uncovering corruption within the police force.

Past stars have included Lennie James, Keeley Hawes and Stephen Graham.

But what details do we know about the forthcoming sixth series? Below is a compilation of all the key information, from release date to the identity of the actor playing the next potentially corrupt officer.

When’s it back?

There is no word on when to expect the new series, but filming is currently underway in Belfast. Excitingly, the first table read for new episodes took place earlier this month.

Going by how long fans have had to wait for previous outings, Line of Duty should be back next spring – the most recent series began in March 2019.

However, writer Jed Mercurio told Radio Times in October that he “would hope” the show returns “sometime in 2020”.

BBC released a behind-the-scenes footage of series six (BBC)

Who has joined the cast?

Kelly McDonald will be playing the shady character being investigated by AC-12. She’ll appear as DCI Joanne Davidson, who is described as “the senior investigating officer of an unsolved murder, whose unconventional conduct raises suspicions at AC-12.” McDonald joins returning cast members Martin Compston (DS Steve Arnott), Vicky McClure (DI Kate Fleming) and Adrian Dunbar (Superintendent Ted Hastings).

Mercurio described Joanne is “the most enigmatic adversary AC-12 have ever faced”.

Following Macdonald’s casting, Compston wrote: “Another magnificent addition to the Line of Duty team. Said it before – [a] huge part of the show’s success is the phenomenal guest actors we’ve had. Kelly Macdonald will be up there with the best of them – what a talent, what a career.”

Also joining the cast is Shalom Brune-Franklin (Our Girl), Andi Osho (Kiri) and Prasanna Puwanarajah (Doctor Foster).

Perry Fitzpatrick, who previously starred opposite McClure in This Is England, will also appear.

What else do we know?

Other than the fact that the cast members appear to be having a lot of fun while filming the show, not much at all. Recent photos from the show’s set in Belfast have shown Compston, McClure and Dunbar mucking about in between takes – and even poking fun at the identity of the villainous “H”.

Mercurio himself has teased the show’s forthcoming plot lines as “ludicrously implausible” – so prepare for plenty more cliffhangers.

Who is “H”?

A big twist in series five revealed that H is not one person, but a group of four high-ranking corrupt law enforcement officials.

We currently know the identity of three of those: DI Matthew Cotton (Craig Parkinson), Chief Superintendent Derek Hilton (Paul Higgins) and the lawyer Gill Biggeloe (Polly Walker), who was arrested in the series five finale.

(World Productions/ BBC / Aidan Monaghan (World Productions/ BBC / Aidan Monaghan)

With Hastings’ name finally cleared, the crew will be attempting to work out the identity of the fourth while also dealing with Joanne.

Will there be another series?

Considering the ratings the show pulls in – more than eight million viewers per episode – it seems like a certainty the BBC will give the drama another few runs.

Mercurio said at the BFI & Radio Times Festival: “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.”