The sixth series of Line of Duty, consisting of seven episodes, began broadcasting on BBC One on 21 March 2021. The story follows the actions of AC-12, led by Superintendent Ted Hastings (Adrian Dunbar) and DI Steve Arnott (Martin Compston), as they investigate DCI Joanne Davidson (Kelly Macdonald) and her team, including former AC-12 officer DI Kate Fleming (Vicky McClure).