With their own detectives at an impasse, London police call on former Kingsmarkham Chief Inspector Wexford, now retired and living with his wife in London, to advise them. Wexford, missing the thrill of a good case, jumps at the chance to sleuth once again. His dogged detective skills and knack for figuring out the criminal mind take him to London neighborhoods, posh and poor, as he follows a complex trail leading back to the original murders a decade ago.