‘Blue Lights’ Returns: Series 4 Release Date, Plot Details, and Full Cast Revealed

The BBC has released the official new artwork and premiere details for the fourth series of its hit police drama Blue Lights, signaling the long-awaited return of the multi-award-winning Belfast-set series on 29 September at 9pm.

Key Details at a Glance

• Release Date: Tuesday, 29 September at 9:00 p.m. on BBC One.
• BBC iPlayer Stream: Full series box set drops at 6:00 a.m. on Tuesday, 29 September.
• Where to Watch: BBC One and BBC iPlayer (Series 1–3 currently available on iPlayer).
• Core Cast Returning: Siân Brooke, Martin McCann, Katherine Devlin, Nathan Braniff, and Richard Dormer in a special guest return.

Three Years In: Constables Face Explosive Secrets and High-Stakes Threat

Three years into their demanding roles as response officers, Constables Grace Ellis, Tommy Foster, and Annie Conlon are pushed to their absolute limits. In Series 4, the team confronts a sinister new threat looming over the streets of Belfast—one that tests the police force’s ability to maintain control.

At the same time, high-stakes drama erupts off the beat as the murder trial of Gerry Cliff exposes a dangerous, long-buried secret. The revelations spark widespread chaos within both the police department and the city’s criminal underworld. As big decisions about their personal and professional futures loom, Grace, Tommy, and Annie must summon the courage to face their greatest threat yet: the truth.

Full Cast Lineup: Returning Stars & Guest Appearances

The critically acclaimed ensemble cast returns for the fourth installment, alongside notable guest stars:

• Siân Brooke (Sherlock, Trying) as Constable Grace Ellis
• Martin McCann (Trespasses, Hostage) as Constable Stevie Neil
• Katherine Devlin (The Day of the Jackal, Vikings) as Constable Annie Conlon
• Nathan Braniff (Blue Lights) as Constable Tommy Foster
• Joanne Crawford (Outlander: Blood of my Blood) as Chief Inspector Helen McNally
• Andi Osho (The Sandman, I May Destroy You) as Sandra Cliff
• Frank Blake (Say Nothing, Normal People) as Shane Bradley
• Abigail McGibbon (Ballywalter) as Tina McIntyre
• Dearbháile McKinney (Blue Lights) as Aisling Byrne
• Neil Keery (How To Get To Heaven From Belfast) as Sergeant Lawrence McCloskey
• Andrea Irvine (Call The Midwife) as Chief Superintendent Nicola Robinson

Special Guest Stars & Guest Returns:

• Richard Dormer (Game of Thrones, The Day of the Jackal) reprising his role as Gerry Cliff in a special one-off episode
• Cathy Tyson (Dune: Prophecy, Black Ops) as private members club owner Dana Morgan
• Hannah McClean (Malpractice) as solicitor Jen Robinson
• Jonathan Harden (Time, Mix Tape) as Inspector ‘Jonty’ Johnston
• Michael Smiley (Bad Sisters, Censor) as C3 intelligence officer Paul ‘Colly’ Collins

Production & Behind the Scenes

Blue Lights Series 4 was commissioned by Lindsay Salt, Director of BBC Drama. The series is produced by Two Cities Television and co-produced by Gallagher Films for BBC iPlayer and BBC One. Executive producers include Stephen Wright (Two Cities Television), Louise Gallagher (Gallagher Films), Declan Lawn, Adam Patterson, and Nick Lambon for the BBC.

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