The Line of Duty is an entertaining British police procedural drama that has been running since 2012. The series is based on the Anti-Corruption Unit 12 (or AC-12), which handles corruption in the police department. In recent years, this BBC series has expanded to be one of the finest crime dramas with an excellent ensemble cast of some of the best British acting talents.The main casts of the series are Martin Compston, Vicky McClure, and Adrian Dunbar. In 2026, the BBC series came back with Season 7 after a 4-year break. It brought back familiar names that fans had come to associate with the show over its six-season run.Line of Duty includes bare-knuckle investigation with rich character growth and stomach-churning twists of a plot that have kept audiences sitting on the edge of their seats at the very start of the pilot episode, up to the very end of the full disclosure.Read more to know belowWho is DI Steve Arnott in Line of Duty?Martin Compston as DI Steve Arnott | Image via Prime VideoIn the TV show, Line of Duty, Martin Compston portrays DI Steve Arnott, the ethical hub of AC 12. Steve begins his days as a counter terrorism officer, but he leaves his position after he declines to speak on a fatal operation. At AC 12, he works to uncover corruption at every level of the police. Steve is intelligent and tenacious, and he tends to push suspects until they crack. On the BBC, Martin opened up about his audition for the show and said,"I only had one audition, and I tend to throw myself into the role of anything I’m doing."His professional work makes his personal life problematic, and he has a hard time experiencing pain following a severe injury. Steve becomes a detective inspector through the seasons as he is promoted to a Detective Sergeant.Who plays DI Kate Fleming?Vicky McClure as DI Kate Fleming | Image via Prime VideoVicky McClure stars as one of the best undercover officers, DI Kate Fleming, in Line of Duty. The pilot episode shows us Kate going straight to the suspects, a feat that she proves through her relationship with them. She often goes undercover in some of the most dangerous units, which puts her life in danger. Kate is daring, intelligent, and sharp in thought, but when a disguise backfires. On Guardian, she said,"I think it was more Lol’s style that [Kate Moss] was commending rather than mine"Kate's personal life is ruined by her obsessive attention towards work, and it destroyed her marriage. She never gives up and keeps on struggling to reveal the truth. She even gets into and out of fights with her employers as she progresses as a Detective Inspector. Kate is an indispensable part of Line of Duty, being the brave and faithful person she is.Adrian Dunbar as Superintendent Ted Hastings View this post on Instagram Instagram PostAdrian Dunbar stars as Superintendent Ted Hastings, the head of AC 12, in Line of Duty. On most occasions, Ted explains that he only wants to arrest dishonest individuals as he is a staunch believer in honest policing. He helps Steve and Kate through challenging cases and assists when the pressure from above mounts.Ted has his own trouble, including money problems and a broken marriage. Sometimes, even his own record is put into doubt, and he himself must be put to the question, just like the suspects whom he usually investigates. Nonetheless, he stands by the unit and the idea of justice.Follow Soap Central for more updates!