The Conan Doyle Notes: The Secret of Jack the Ripper uncovers clues as to why the dog did not bark in the night... Sherlock Holmes concluded that it was because the intruder was known to the dog. Madsen's new mystery questions whether the identity of one of the greatest criminals of all time, Jack the Ripper, was deduced by Conan Doyle. Conan Doyle was already famous with his popular Sherlock Holmes stories when Jack the Ripper struck London in October 1888. So why was Conan Doyle silent about this case? This thrilling adventure may well hold the key...