Line of Duty, After a mistaken shooting throughout a counter-terrorist operation, Detective Sergeant Steve Arnott is transferred to AC-12, a police anti-corruption unit semiconductor diode by Superintendent Hastings. aboard Detective Constable Kate Fleming, they’re assigned to steer Associate in Nursing investigation into the alleged corruption by a well-liked and eminent officer, Detective Chief Inspector Tony Gates. whereas Gates smartly manipulates his unit’s figures, DS Arnott queries whether or not Gates is being created a victim for a culture of institutionalized spin, or is guilty of darker corruption.