The actor will return as Detective Chief Superintendent Patricia Carmichael in episode five of the current series of Line of Duty.
Viewers will remember no-nonsense DCS Carmichael from series five, where she was brought in as an independent investigator from AC-3 after suspicions mounted over the integrity of Superintendent Ted Hastings.
Now with Ted’s forced retirement looming, is Carmichael in position to take control? And with the restructure of the anti-corruption units, is this the end of AC-12?
Speaking about returning to Line of Duty, Anna Maxwell Martin said "Pat’s back, I can’t remember what she’s doing there, nor would I be allowed to blab, but suffice to say she’s got some new clobber and she’s ready to bust some balls."
Line of Duty continues Sunday at 9pm on BBC One