Steve Arnott is a young officer who’s fallen foul of his superiors for refusing to help in the cover-up of an operation that ended in the shooting of an innocent father. He seems ideal to join AC-12, an anti-corruption police unit, just as it starts to investigate Detective Chief Inspector Tony Gates, the regional force’s Officer of the Year.

After a mistaken shooting during a counter-terrorist operation, Detective Sergeant Steve Arnott is transferred to AC-12, a police anti-corruption unit. Alongside Detective Constable Kate Fleming ,they are assigned to lead an investigation into the alleged corruption by a por and successful officer, Detective Chief Inspector Tony Gates. While Gates cleverly manites his unit's figures, DS Arnott questions whether Gates is being made a scapegoat for a culture of institutionalized spin, or is guilty of darker corruption.