Blue Lights is returning to BBC One and BBC iPlayer for a fourth series, with the BBC releasing new artwork ahead of the drama's highly anticipated comeback.
The multi-award-winning police drama will return on Tuesday, September 29 at 9pm on BBC One.
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All episodes will also be available to stream from 6am on BBC iPlayer on the same day.
When is Blue Lights Series 4 on BBC One and BBC iPlayer?
Blue Lights Series 4 starts on Tuesday, September 29 at 9pm on BBC One.
Viewers who want to watch the entire series at once will be able to find all episodes on BBC iPlayer from 6am that morning.
The previous series of Blue Lights are also available to watch on BBC iPlayer.
What is Blue Lights Series 4 about?
Series four picks up three years into the careers of response officers Grace Ellis, Tommy Foster and Annie Conlon.
The trio are now operating at their limit as they face a new threat on the streets which the police are struggling to control.
Meanwhile, the murder trial of Gerry Cliff begins to expose a dangerous secret which has remained buried for years.
The revelations cause chaos both within the police and across Belfast's criminal underworld.
As Grace, Tommy and Annie are forced to make major decisions about their futures, they must find the courage to confront the biggest threat they have faced yet.
The BBC teases that threat as being the truth.
Who is in the Blue Lights Series 4 cast?
Siân Brooke returns as Grace Ellis, with Martin McCann playing Stevie Neil.
Katherine Devlin is back as Annie Conlon, while Nathan Braniff returns as Tommy Foster.
Joanne Crawford plays Chief Inspector Helen McNally, while Andi Osho returns as Sandra Cliff.
The returning cast also includes 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.
Richard Dormer will also return as Gerry Cliff for a special one-off episode.
Cathy Tyson joins the returning cast as private members club owner Dana Morgan, while Hannah McClean plays solicitor Jen Robinson.
Jonathan Harden returns as Inspector 'Jonty' Johnston and Michael Smiley plays C3 intelligence officer Paul 'Colly' Collins.
What happens in Blue Lights Series 4?
The new series will see Grace, Tommy and Annie facing an increasingly difficult situation as they continue their work as response officers.
The murder trial surrounding Gerry Cliff will also become central to the story as a long-buried secret threatens to have consequences far beyond the courtroom.
The revelations will affect both the police and the criminal underworld, forcing the characters to question who they can trust.
The fourth series will once again combine the personal lives of its police officers with the dangers and pressures of their work.
Blue Lights is produced by Two Cities Television and co-produced by Gallagher Films for BBC iPlayer and BBC One.
The series was commissioned by Lindsay Salt, Director of BBC Drama.
Stephen Wright, Louise Gallagher, Declan Lawn and Adam Patterson are executive producers, alongside Nick Lambon as executive producer for the BBC.
BBC Studios is handling global sales for Series 4, as well as the previous series.
Blue Lights has been sold in more than 160 territories worldwide.
Blue Lights Series 4 starts Tuesday, September 29 at 9pm on BBC One, with all episodes available from 6am on BBC iPlayer.
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