Books like the valley of fear

The Valley of Fear is the fourth and final Sherlock Holmes novel by Sir Arthur Conan Doyle. It is loosely based on the Molly Maguires and Pinkerton agent James McParland. The story was first published in the Strand Magazine between September 1914 and May 1915. The first book edition was copyrighted in 1914, and it was first published by George H. Doran Company in New York on 27 February 1915, and illustrated by Arthur I. Keller.

Sherlock Holmes receives a cipher message from Fred Porlock, a pseudonymous agent of Professor Moriarty. After Porlock sends the message, however, he changes his mind for fear of Moriarty's discovering that he is a traitor. He decides not to send the key to the cipher, but he sends Holmes a note telling of this decision. From the cipher message and the second note, Holmes is able to deduce that it is a book cipher and that the book used for the encryption is a common book, large (with at least 534 pages), printed in two columns per page, and standardised. An almanac fits these conditions exactly.