Arthur Conan Doyle 
The Valley of Fear [EPUB ebook] 

Serialised from September 1914 to May 1915 in the
Strand Magazine, 'The Valley of Fear’, is the fourth and final Sherlock Holmes novel by Sir Arthur Conan Doyle.
At the beginning of this novel, Holmes gets a message from one of Professor Moriarty’s agents—Fred Porlock. From time to time, Porlock sends Sherlock inside information about Moriarty’s endeavors. Despite the fact that the law sees Moriarty as innocent, Sherlock firmly believes him to be the puppet master of a criminal underworld. Sherlock enlists the help of his friend and sidekick, Dr. Watson, to decode Porlock’s message; from it, they learn that the life of John Douglas, who resides at Birlstone, is in danger…