DI Jack Regan (Ray Winstone) and DC George Carter (Ben Drew) realize their squad had been fooled by Francis Allen (Paul Anderson). Allen WAS part of the jewelery job and the bank heist that led to the murder of Nancy Lewis (Hayley Atwell), one of their friends and fellow officer. Makin Trebolt (Kevin Michaels), a Serbian criminal with a habit of murdering witnesses killed her (he also killed the hostage at the jewelery job because she happened to know him).
Though technically suspended from the case after Lewis' death, Carter and Regan investigate further and realize that Allen and Trebolt are going to escape on Allen's boat. The two attempt to escape and get into a car chase with Regan and Carter. They crash though Trebolt's car eventually runs Carter over. When he opens the door to finish Carter off, Regan shoots Trebolt dead. When given a chance to get revenge against Allen for Lewis' death, Regan shows he is still a cop only telling Allen "You're nicked."
The last scene is Regan going back on the job with his squad mates. Since he had turned out to be right about Allen and brought him to justice along with Trebolt, he has been reinstated to full active duty.