The BBC crime drama follows DI Steve Arnott (Martin Compston), DI Kate Fleming (Vicky McClure), and Superintendent Ted Hastings (Adrian Dunbar) as they fight to combat corrupt "bent" coppers. This season introduces Joanne Davidson (Kelly Macdonald), a rogue Detective Chief Inspector with an obscure past. Fiery characters and dialogue, thrilling chase scenes, and unpredictable plot-twists make this one of the most binge worthy crime dramas ever.