The Valley of Fear is the last Sherlock Holmes novel by Sir Arthur Conan Doyle, first published in book form in 1915. Loosely based on the activities of the secret Irish organization that was the Molly Maguires and of undercover Pinkerton agent James McParland, the novel is split into two parts. Firstly Holmes investigates a murder and finds that the body belongs to a different man. In the second part, the story of the man who was originally thought to have been the murder victim is given.