Kelly Macdonald will star in the cast of series 6 of BBC One's Line Of Duty.
The BBC has announced she will guest lead the next set of episodes.
Kelly will play Detective Chief Inspector Joanne Davidson, the senior investigating officer of an unsolved murder, whose unconventional conduct raises suspicions at AC-12.
The actress is best known for her roles in Trainspotting, Gosford Park, State Of Play, No Country For Old Men, Boardwalk Empire and, most recently, The Victim and Giri/Haji.
Kelly joins returning cast members Martin Compston, Vicky McClure and Adrian Dunbar on the hit show, which will begin filming its sixth series in 2020.
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, CEO and Creative Director of World Productions, added: “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.”
Piers Wenger, Controller of BBC Drama, commented: “We’re delighted that Kelly Macdonald is coming on board for series six.
"She’s one of the UK’s most versatile actors and we’re excited for viewers to see what Jed’s scripts have in store for her when she joins the Line Of Duty team.”
Series 5 of Line Of Duty concluded in May of this year, with viewing figures topping 13.7 million with catch up on TV and online included.
Further details about Series 6 - including when it will air - are yet to be confirmed.