From a manuscript believed to be the work of John H. Watson, MD When a series of bizarre accidents befall small shopkeepers who have recently taken precautions to protect their premises, Sherlock Holmes is the first to discern a pattern, to the befuddlement of his most loyal friend. It seems someone is running a protection racket, and more, murder is involved, so Holmes teams up with a New York detective who has travelled to London to get to the bottom of the Rule of Nine.