Richard Dormer is returning to Blue Lights for its fourth series

What will we learn from the murder trial of Gerry Cliff?

Blue Lights fans are in for a treat when the hit Belfast police drama returns to BBC One for its fourth series, as it has been confirmed that Richard Dormer, who played Gerry Cliff in the first series, before being tragically shot by a local gangster while on patrol will be returning to the role.

The murder trial of Gerry Cliff will expose a dangerous and long-buried secret that leads to chaos both inside the police and across the criminal underworld.

Three years into their jobs as response officers, Constables Grace Ellis, Tommy Foster, and Annie Conlon are operating at their limit, facing a new threat on the streets that the police can barely control. Meanwhile the

As they grapple with big decisions about their future, Grace, Tommy and Annie must find the courage to face the greatest threat they have ever encountered: the truth.

Series four will also see the return of Hannah McClean as solicitor, Jen Robinson and Jonathan Harden as disgraced former Inspector, Jonty, in an episode that will answer important questions from the past.

Returning cast members include Siân Brooke as Grace, Martin McCann as Stevie, Katherine Devlin as Annie, Nathan Braniff as Tommy, Joanne Crawford as Helen McNally, Andi Osho as Sandra, Frank Blake as Shane, Abigail McGibbon as Tina, Dearbháile McKinney as Aisling and Andrea Irvine as Nicola.

Also returning are Cathy Tyson as private members club owner, Dana Morgan and Michael Smiley as C3 intelligence officer, Paul ‘Colly’ Collins.

Speaking about his return, co-creators and co-writers, Declan Lawn and Adam Patterson, said "We’re very excited to bring this series of Blue Lights to audiences. It reveals a lot of dark secrets, examines what justice looks like in Belfast today, and ties together the past, present, and futures of Grace, Annie and Tommy in an action-packed story. We can’t wait to start filming it!"

To which Stephen Wright, Two Cities Television and Louise Gallagher, Gallagher Films added "We are delighted to get the cast and crew back together for series four and welcome some new faces to the Blue Lights team. The appreciation for the show means so much to everyone involved and illustrates the power of fantastic teamwork.”

And Nick Lambon, BBC Drama Commissioning Editor, UK & Northern Ireland, said "Blue Lights has gripped and entertained millions of viewers across three series and Declan and Adam’s scripts will once again have us all on the edge of our seats. Gerry Cliff was such an integral part of series one so to have Richard Dormer back alongside our talented cast is a dream come true. We are over the moon to be back filming in Belfast, and with so many twists and turns in store, fans of Blue Lights have plenty to look forward to."

Produced by Two Cities Television and co-produced by Gallagher Films, the fourth series of Blue Lights will be produced by Brendan Mullin, with Angela Griffin directing the first three episodes and episodes 4-6 will be directed by Sam O'Mahoney.

It'll be executive produced by Stephen Wright for Two Cities Television, Louise Gallagher for Gallagher Films, Declan Lawn, Adam Patterson, and Nick Lambon for the BBC.

Blue Lights will return to BBC One