Sir Edmund Carstairs requests the aid of Sherlock Holmes when a member of the Flat Cap gang, an Irish thug from Boston, arrives in London to extort him or worse. Holmes uses some London street urchins as his eyes and ears only to have one young boy turn up murdered. Then things turn really dicey for the famous detective. Horowitz does a surprisingly competent job of recapturing Arthur Conan Doyle’s style and characterizations, though Dr. Watson comes off as a little more doltish than necessary. It isn’t great literature, but it is a satisfying read, nonetheless, if you are in the mood for a Holmse-ian mystery. If you can listen to the audio book version read by Derek Jacoby.