Blue Lights Series 4: Official Trailer Reveals A New Threat As Grace, Tommy And Annie Face Their Biggest Challenge Yet

The wait for Blue Lights Series 4 is almost over, and the newly released official trailer and artwork offer the first glimpse of what lies ahead for the Belfast police officers.

The BAFTA- and RTS-winning drama will return to BBC iPlayer and BBC One in autumn 2026, with Grace Ellis, Tommy Foster and Annie Conlon now three years into their careers as response officers.

But experience has not made their jobs any easier. Instead, they are pushed closer to their limits as a new threat emerges on the streets — one that the police are struggling to contain.

At the same time, the murder trial of Gerry Cliff begins exposing a dangerous secret that has remained buried for years. As the revelation sends shockwaves through both the police and Belfast’s criminal underworld, Grace, Tommy and Annie are forced to confront difficult decisions about where their futures lie.

And this time, the greatest danger may not simply be what is happening around them. It may be the truth they are about to uncover.

A New Chapter For Grace, Tommy And Annie

Series 4 picks up with the three officers three years into their work as response officers.

Grace Ellis, played by Siân Brooke, Tommy Foster, played by Nathan Braniff, and Annie Conlon, played by Katherine Devlin, have gained experience since the beginning of the series. But their latest challenges threaten to push all three further than ever before.

A new danger is taking hold on the streets, creating a situation that the police are finding increasingly difficult to control.

The pressure is intensified by developments surrounding Gerry Cliff’s murder trial. What emerges during the proceedings threatens to expose a long-hidden secret, with consequences that extend far beyond the courtroom.

The revelation creates turmoil within the police while also destabilising the criminal world around them.

The Return Of A Major Cast

The fourth series brings back many of the show’s established characters.

Alongside Siân Brooke as Grace Ellis, Martin McCann returns as Stevie Neil, Katherine Devlin as Annie Conlon and Nathan Braniff as Tommy Foster.

The returning cast also includes Joanne Crawford as Chief Inspector Helen McNally, Andi Osho as Sandra Cliff, Frank Blake as Shane Bradley, Abigail McGibbon as Tina McIntyre, Dearbháile McKinney as Aisling Byrne, Neil Keery as Sergeant Lawrence McCloskey and Andrea Irvine as Chief Superintendent Nicola Robinson.

The series will also feature the return of Richard Dormer as Gerry Cliff in a special one-off episode.

Other returning performers include Cathy Tyson as private members’ club owner Dana Morgan, Hannah McClean as solicitor Jen Robinson, Jonathan Harden as Inspector “Jonty” Johnston and Michael Smiley as C3 intelligence officer Paul “Colly” Collins.

A Six-Episode Fourth Series

Series 4 consists of six 60-minute episodes for BBC iPlayer and BBC One.

The drama is once again co-created, written and executive produced by Declan Lawn and Adam Patterson. Stephen Wright returns as co-creator and producer through Two Cities Television, while Louise Gallagher serves as co-creator and co-producer through Gallagher Films.

The production is supported by Northern Ireland Screen.

Brendan Mullin, whose previous credits include In Flight and Wreck S2, is the producer for the fourth series.

The first three episodes are directed by Angela Griffin, who previously directed episodes of Blue Lights Series 3 and is also known for Waterloo Road. The final three episodes are directed by Sam O’Mahony, director of The Wise Guy.

The Team Behind The Return

The fourth series was commissioned by Lindsay Salt, Director of BBC Drama.

Executive producers are Stephen Wright for Two Cities Television, Louise Gallagher for Gallagher Films, Declan Lawn and Adam Patterson. Nick Lambon serves as the BBC’s executive producer.

The production continues the collaboration between Two Cities Television and Gallagher Films, with Two Cities Television forming part of the STV Studios family of production labels.

Blue Lights Continues Its International Reach

The Belfast-set drama has already established an international audience, with BBC Studios handling global sales for Series 4 as well as the previous series.

To date, Blue Lights has been sold in more than 160 territories, extending the reach of the award-winning police drama well beyond its BBC home.

Now, with Series 4 heading to BBC iPlayer and BBC One in autumn 2026, the focus returns to Grace, Tommy and Annie — and the increasingly dangerous world they are trying to police.

This time, they are not simply facing another difficult case.

They are being forced to confront the truth.