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 novel starts when Sherlock Holmes receives a mysterious ciphered message from an agent to Professor Moriarty using the pseudonym Fred Porlock. Together Holmes and Watson decipher Porlock's message which relates that a man named John Douglas, residing at Birlstone, is in danger. Soon inspector Alec MacDonald of Scotland Yard ask Holmes to help in the case. Holmes tells MacDonald of Porlock warning, suggesting Professor Moriarty's involvement. However, MacDonald doesn't fully believe that the educated and well respected Moriarty is a criminal.