The Beeb are remaining tight-lipped for now with further details about their characters.
Returning are lead stars Siân Brooke and Martin McCann who play Grace Ellis and Stevie Neil respectively.
Katherine Devlin, Nathan Braniff, Joanne Crawford, Andi Osho (Sandra), Frank Blake, Abigail McGibbon, Dearbháile McKinney and Andrea Irvine will all reprise their roles too.
Blue Lights follows three rookie coopers who work in Belfast dealing with street an drug crime.
Its most recent series aired in April last year, but with filming only taking place now on the third instalment, fans will have a while to wait until the watch it all play out.
Series two averaged 5.6M viewers across the series, while episode one’s 7M made it the BBC’s fourth biggest drama launch last year
Official trailer for BBC's Blue Lights Series 2
BBC crime dramas
The BBC is reopening case files on an all-star line-up of crime dramas this summer.
Campion: Aired from 1989 to 1990, this detective drama series was adapted from novels by Margery Allingham and stars Peter Davison.
Dalziel And Pascoe: A gritty detective drama series about a mismatched pair of policemen, based on the award-winning books by Reginald Hill. Aired from 1996 to 2007.
Death In Paradise: A misanthropic detective inspector is assigned to a Caribbean island against his will. Premiered in 2011 and is still on air to this day.
Happy Valley: Created by Sally Wainwright, this northern noir follows Sarah Lancashire as Sgt Catherine Cawood – tough, defiant and facing her traumatic past.
Hinterland: Welsh drama starring Richard Harrington. Brooding DCI Tom Mathias uncovers secrets – and links to his troubled past amid mountainous terrain and close-knit villages. Aired from 2013 to 2016.
Inspector Lynley Mysteries: Based on the novels of Elizabeth George, this drama series is about upper-crust DI Thomas Lynley and working class DS Barbara Havers. Aired from 2001 to 2007.
Jonathan Creek: Starring comedian Alan Davies, this comedy-drama series follows a inventor of magic tricks who is often called in to solve puzzling murders. Aired from 1997 to 2016.
Law & Order: Originally broadcast in 1978, this four-part drama series is about the British judicial system. Stars include Peter Dean and Derek Martin.
Life On Mars: Beguiling science-fiction police drama following a Manchester policeman who travels back to 1973 following a car accident. Stars John Simm and Philip Glenister. Aired from 2006 to 2007.
Shetland: Detective drama starring Douglas Henshall, Ashley Jensen and Alison O'Donnell, showcasing the dark side of one of the most beautiful places on earth. Premiered in 2013 and is still on air to this day.
The Cops: Set in the fictional northern town of Stanton, this acclaimed, provocative police drama stars Katy Cavanagh, Rob Dixon and John Henshaw. Aired from 1998 to 2001.
Waking The Dead: With a cast including Trevor Eve, Sue Johnston and Wil Johnson, this series follows a cold case team who unearths sleeping secrets, but sometimes the past is best left buried. Aired from 2000 to 2011.
Wallander: Starring Sir Kenneth Branagh, Kurt Wallander is unable to unsee the dark crimes he's tasked to investigate while Wallander's job comes at a cost to his family and relationships. Aired from 2008 to 2016.