After receiving a pseudonymous cipher from one of Moriarty's henchmen, Holmes and Watson must unravel the mysterious murder of a country gentleman. The puzzling case gives the detective the perfect opportunity to demonstrate his skills in observation, forensics, and deduction. This electrifying novel features themes of ethical ambiguity and makes political commentary on terrorist activity. First published in between 1914 and 1915, this captivating detective-fiction novel presents an intricate crime and sets the reader the impossible challenge of cracking the case before Holmes can solve it. This edition features a specially commissioned introduction alongside an article by Arthur Conan Doyle and an essay on the history of detective fiction by S.S. Van Dine.