Filming for the fourth series of BBC drama Blue Lights takes place in west Belfast. Actors Katherine Devlin and Frank Blake appeared on location on Monday.

The production by Two Cities Television and Gallagher Films airs on BBC iPlayer and BBC One. Siân Brooke returns as Grace Ellis. The storyline centres on constables Grace Ellis, Tommy Foster, and Annie Conlon three years into their PSNI positions.

The officers face street threats while a murder trial proceeds over the shooting of Sergeant Gerry Cliff from the first series end. The trial reveals a past secret affecting police and criminal networks.

Richard Dormer reprises Sergeant Gerry. Hannah McClean returns as solicitor Jen Robinson. Jonathan Harden plays former inspector Jonty.

Creators Declan Lawn and Adam Patterson state the episodes disclose hidden matters and bring back characters to address prior events.

Blue Lights topped drama viewership across Northern Ireland broadcasters and streamers in 2023 and 2024. BBC Drama commissioning editor Nick Lambon noted the scripts keep viewers engaged.