Kelly Macdonald will star in the next series of Line Of Duty as the “most enigmatic adversary AC-12 have ever faced”.

The Trainspotting and Boardwalk Empire actress will play Detective Chief Inspector Joanne Davidson, the senior investigating officer of an unsolved murder, whose unconventional conduct raises suspicions at the anti-corruption unit.

Macdonald will join series leads Martin Compston, Vicky McClure and Adrian Dunbar when filming on the sixth season of the BBC One crime drama starts next year.

The Scottish screen star, 43, is best known for roles in the Trainspotting films, lavish TV drama Boardwalk Empire and films Gosford Park, No Country For Old Men and Intermission.

Line Of Duty writer and showrunner Jed Mercurio said: “We’re honoured that Kelly Macdonald will join Martin, Vicky and Adrian in series six of Line Of Duty.

“DCI Joanne Davidson will prove the most enigmatic adversary AC-12 have ever faced.”

Simon Heath, chief executive and creative director of Line Of Duty’s production company World Productions, said: “The Line Of Duty team have always been huge fans of her work, so we’re thrilled Kelly has agreed to join us this series to pit her wits against AC-12.”

Macdonald was described as “one of the UK’s most versatile actors” by controller of BBC drama Piers Wenger.

The fifth series of the popular police procedural aired earlier this year, with Stephen Graham in the guest lead as Detective Sergeant John Corbett.

Its final episode drew more than nine million viewers when it aired in May, making it the most-watched drama since Mercurio’s Bodyguard, which aired in 2018.