Dead Letter — Douglas Clark

Detective Chief Inspector Bill Green of Scotland Yard receives an anonymous letter from a former army comrade who has inadvertently witnessed a murder. The witness has good reason to maintain anonymity, because one of the accomplices to the murder happens to be a local policeman. Green and his partner, Detective Chief Superintendent George Masters, face one of the greatest challenges of their careers as they launch a subtle investigation without arousing the suspicion of a corrupt colleague who is dangerously adept in using his professional police skills for evil purposes.