“The Valley of Fear” is the fourth and final novel starring Sherlock Holmes and John Watson, written by English author Sir Arthur Conan Doyle (1859-1930). Like all previous Sherlock Holmes stories, it was first published in serialized form between 1914 and 1915, and later in book form. A mysterious murder takes place and Holmes and Watson must use all their wits to piece the puzzle together. The novel makes use of all the usual story beats of a Sherlock Holmes adventure but goes even further, introducing new narrative structures and the character of Moriarty, who would become in time Holmes' greatest adversary.