Last Updated: 30 September 2026
Blue lights season 4 is finally here, and fans of the BBC’s Belfast police drama barely had to wait. The new six-part series landed on BBC iPlayer on Tuesday 29 September 2026, exactly a year after series 3 finished, with the opening episode also airing on BBC One the same evening. If you have been following Grace, Annie and Tommy from their first days on the beat, this is the series you have been waiting for, because it changes everything we thought we knew about the show’s biggest mystery. The new run jumps three years forward, throws the officers into their toughest challenge yet, and brings back a character many viewers thought was gone for good.
In this guide, we round up everything confirmed about the new series so far. You will find the release details, a spoiler-light plot breakdown, the full cast list, behind-the-scenes news and a quick recap of series 1 to 3. Whether you are a long-time fan or a newcomer tempted by the hype, here is your complete guide to the new series.
There is a reason the show is trending again. Few British dramas balance gritty realism with genuine heart the way this one does, and the promise of long-buried secrets finally coming to light has sent fan theories into overdrive. With all six episodes available at once, there has never been a better moment to dive in — or to revisit Belfast from the very beginning.
When is Blue Lights season 4 out? It is out now. All six episodes were released on BBC iPlayer at 6am on Tuesday 29 September 2026, with the first episode also broadcast on BBC One at 9pm that night. That is the full release — no weekly wait for iPlayer viewers, so you can stream the entire series today.
What Is Blue Lights?
Blue Lights is a BBC police drama set in Belfast, Northern Ireland. It follows rookie — and now experienced — response officers of the Police Service of Northern Ireland (PSNI) as they patrol the streets, tackling everything from petty theft to organised crime while building fragile relationships with the local community.
The series was created and written by Declan Lawn and Adam Patterson, the duo behind The Salisbury Poisonings. It first aired in March 2023 and quickly earned a reputation as one of the most authentic crime dramas on British television, winning BAFTA recognition and strong viewing figures. The new run is produced by Two Cities Television with Gallagher Films for BBC One and BBC iPlayer.
What sets the drama apart is its realism. The scripts draw on the real experiences of PSNI officers, and the show does not shy away from the unique pressures of policing in Northern Ireland. Critics have praised its grounded performances and its willingness to let quiet character moments breathe between the high-stakes set pieces. That reputation is exactly why each new series arrives with such high expectations.
When Did Blue Lights Season 4 Come Out?
The BBC confirmed the air date in mid-September 2026, and the wait was shorter than fans expected. Blue lights season 4 arrived as a full box set on BBC iPlayer at 6am on Tuesday 29 September 2026, while episode one also aired on BBC One at 9pm the same night (Radio Times confirmed the release details).
The timing is notable. There was a 17-month gap between series 2 and 3, because the writers were getting both series mapped out at the same time. Series 4, by contrast, lands almost exactly a year after series 3 ended on 3 November 2025. Fans have had one of the shortest waits in the show’s history.
- Series 1: 27 March 2023 – six episodes
- Series 2: 15 April 2024 – six episodes
- Series 3: 29 September to 3 November 2025 – six episodes
- Series 4: 29 September 2026 – six episodes, all on iPlayer
What Is the Plot of the New Series?
The official BBC synopsis sets up a darker, more pressurised chapter for the team. Three years into their jobs as response officers, Constables Grace Ellis, Tommy Foster and Annie Conlon are operating at their limit. They face a new threat on the streets that the police can barely control.
At the same time, the murder trial of Gerry Cliff exposes a dangerous and long-buried secret. The revelations send chaos through both the police and Belfast’s criminal underworld. As the trio wrestle with big decisions about their future, they must find the courage to face what the BBC calls the greatest threat they have ever encountered: the truth.
Early coverage of the opening episode also points to tensions around a migrant resource centre, where an increasingly hostile anti-immigration movement spreads hateful rhetoric on social media. It is classic Blue Lights territory — ripped-from-the-headlines issues handled through the eyes of ordinary officers.
The three-year time jump is a bold move, and it matters for the characters. Grace, Tommy and Annie are no longer rookies learning the ropes — they are experienced officers carrying the weight of everything they have seen. The official synopsis hints that each of them faces major decisions about their future, which suggests the new series will test not just their courage on the streets, but their commitment to the job itself.
Star Siân Brooke has teased that the return of Gerry Cliff uncovers “deep dark truths” for Grace and her colleagues. Without spoiling anything, the new story weaves the past, present and future of the three leads into what the writers describe as an action-packed run.
Who Is in the Cast of the New Series?
The main trio all return for blue lights season 4, alongside a strong ensemble of familiar faces and a few notable comebacks (see the full Radio Times cast guide).
- Siân Brooke as Grace Ellis
- Martin McCann as Stevie Neil
- Katherine Devlin as Annie Conlon
- Nathan Braniff as Tommy Foster
- Joanne Crawford as Chief Inspector Helen McNally
- Andi Osho as Sandra Cliff
- Frank Blake as Shane Bradley
- Abigail McGibbon as Tina McIntyre
- Cathy Tyson as Dana Morgan
- Michael Smiley as intelligence officer Paul “Colly” Collins
- Hannah McClean as solicitor Jen Robinson
- Jonathan Harden as Inspector Jonty Johnston
- Dearbháile McKinney as Aisling Byrne
- Neil Keery as Lawrence McCloskey
- Andrea Irvine as Nicola Robinson
The biggest talking point is the return of Richard Dormer as Gerry Cliff. Gerry was murdered in series 1, shot by a local gangster while on patrol, but his shadow has loomed over every series since. Dormer returns for a special one-off episode tied to Gerry’s murder trial, which the BBC says will answer lingering questions from the past.
Two more returning faces deserve a mention. Hannah McClean is back as solicitor Jen Robinson after sitting out series 3, and Jonathan Harden returns as disgraced former Inspector Jonty Johnston — seen for the first time since series 1. Their involvement ties directly into the episode that promises to answer lingering questions about Gerry’s death.
BBC Drama Commissioning Editor Nick Lambon said the return was a dream: “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.”
Filming and Renewal: How the New Series Was Made
Here is a reveal many newer fans miss: series 3 and 4 were commissioned together. Back in February 2024, before series 2 had even aired, the BBC ordered two more six-part runs. BBC Director of Drama Lindsay Salt said at the time: “We were bowled over by the reaction to Blue Lights and I’m really pleased to be confirming our commitment to bring two more series of our beloved Belfast drama to air.”
Production on the new series moved fast. The script read-through took place in January 2026, with filming starting in Belfast just days later. The BBC released first-look images on 22 July 2026 — showing Grace, Stevie, Annie and Tommy back on the streets — followed by a full trailer in August 2026.
Behind the camera, creators Declan Lawn and Adam Patterson once again wrote all six episodes. Episodes 1 to 3 were directed by Angela Griffin, with Sam O’Mahoney directing episodes 4 to 6, and Brendan Mullin producing. The drama is now sold in more than 160 territories worldwide, which explains why the BBC moved so quickly to lock in the new series.
Filming on location in Belfast remains central to the show’s identity. The city is practically a character in its own right, from the estates the officers patrol to the station corridors where the biggest decisions are made. Local crews and Northern Ireland Screen support have helped the production stay rooted in the place it portrays, and that authenticity is a big part of why international audiences have embraced it.
Blue Lights Series 1–3 Recap: Catch Up Before the New Series
New to the show, or just need a refresher? This quick recap will get you ready for blue lights season 4 in minutes.
| Series | Aired | Key storyline |
|---|---|---|
| Series 1 | March 2023 | Grace, Annie and Tommy join as rookie response officers in Belfast. Sergeant Gerry Cliff is murdered on patrol, a death that haunts the whole series. |
| Series 2 | April 2024 | The officers are more seasoned but face loyalist paramilitaries, corruption and personal crises as the criminal underworld tightens its grip. |
| Series 3 | Sept–Nov 2025 | The team confronts organised crime networks and shifting loyalties, ending with the stage set for Gerry Cliff’s murder trial. |
- Start with series 1 if you have never watched — Gerry Cliff’s story is the emotional engine of everything that follows.
- Series 2 deepens the criminal underworld and the officers’ personal lives.
- Series 3 is essential viewing before series 4, because it leads directly into the murder trial storyline.
- All three earlier series are streaming on BBC iPlayer right now.
How to Watch Blue Lights Season 4: 4 Simple Steps
Watching the new series in the UK could not be easier. All six episodes are available as a box set.
- Head to BBC iPlayer on your TV, phone, tablet or computer and sign in with your free BBC account.
- Search for “Blue Lights” and select series 4 — all six episodes are ready to stream.
- Check you are covered by a TV licence, which you need to watch or download any BBC iPlayer content in the UK.
- Prefer live TV? Episode one aired on BBC One at 9pm on 29 September 2026, with further episodes following on the channel.
Outside the UK, the series has been sold in more than 160 territories. In the United States, BritBox will premiere the new series on 12 November 2026, releasing one episode weekly through 17 December. Viewers in other countries should check their local streaming services, as the BBC Studios global sales deal means the show keeps reaching new audiences every year. Wherever you are, the safest bet for the latest availability is your regional BritBox or BBC-affiliated platform.
Will There Be a Blue Lights Season 5?
This is the question every fan is asking, and the honest answer is that nothing has been confirmed yet. Series 3 and 4 were the two runs ordered back in February 2024, so series 4 completes that commission.
There are reasons for optimism, though. The show is a BAFTA-winning hit, it has been sold in more than 160 territories, and series 4 landed just a year after series 3 — a sign the BBC is keen to keep momentum going. Creators Declan Lawn and Adam Patterson also have a new BBC political thriller, D-Notice, in the works, so their dance card is full either way.
For now, the best thing fans can do is watch the new series — strong viewing figures are what convince the BBC to order more.
In a related development, Lawn and Patterson have also been commissioned by the BBC to make D-Notice, a six-episode political thriller drawn from their past careers in investigative journalism. It will be their third BBC project after The Salisbury Poisonings and Blue Lights, and the first commission from their new production company Hot Sauce Pictures. It is unclear whether the new show affects the future of the police drama — the pair could yet work on both at the same time.
Frequently Asked Questions
When is Blue Lights season 4 out?
Blue lights season 4 is out now. All six episodes were released on BBC iPlayer at 6am on Tuesday 29 September 2026, and the first episode also aired on BBC One at 9pm that evening.
How many episodes are in Blue Lights season 4?
There are six hour-long episodes in blue lights season 4, the same as every previous series. All six dropped on BBC iPlayer at once, so you can binge the whole series or take it one episode at a time.
Is Richard Dormer in Blue Lights season 4?
Yes. Richard Dormer returns as Gerry Cliff in blue lights season 4 for a special one-off episode. Gerry was murdered in series 1, and the new series follows his murder trial, which exposes a dangerous secret buried for years.
Where can I watch Blue Lights season 4?
In the UK, you can watch blue lights season 4 on BBC iPlayer, where all six episodes are streaming now, and on BBC One. In the US, the series premieres on BritBox on 12 November 2026 with weekly episodes through 17 December.
Do I need to watch series 1 to 3 before Blue Lights season 4?
It is not strictly required, but it is strongly recommended. Blue lights season 4 builds directly on earlier storylines — especially Gerry Cliff’s murder in series 1 and the events of series 3 that lead into his trial. All three earlier series are on BBC iPlayer.
Will there be a Blue Lights season 5?
No fifth series has been announced. Blue lights season 4 completes the two-series order the BBC made in February 2024. The show’s strong ratings and international sales make a renewal possible, but fans will have to wait for an official announcement.
Final Thoughts
Blue lights season 4 is the series the show has been building towards since 2023. With Gerry Cliff’s murder trial finally taking centre stage, a time jump that raises the stakes for Grace, Annie and Tommy, and Richard Dormer’s emotional return, this is essential viewing for every crime drama fan. All six episodes are streaming on BBC iPlayer right now — so grab your remote, settle in, and start watching blue lights season 4 tonight. Then come back and tell us what you thought of that opener.
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