Red Riding: The Year of Our Lord 1980 (2009)

With a serial killer claiming victim 13 and rumors of corruption in their force, the West Yorkshire cops are told to cooperate with a team from outside - Peter Hunter and two hand-picked associates. Hunter gets little help but plunges ahead, discovering that one of the 13 victims may have a different killer. This part of the investigation leads to late-night calls, another murder, and bureaucratic moves to push Hunter aside: he may be getting close, not to the serial killer but to bad apples in the force. Christmas approaches.