"Mediocrity knows nothing higher than itself; but talent instantly recognizes genius." ~ The Valley of Fear

The Valley of Fear is the fourth and final Sherlock Holmes novel by British writer Arthur Conan Doyle. It is loosely based on the Molly Maguires and Pinkerton agent James McParland. The story was first published in 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.

Doyle said the iconic book had "two parts and a coda". The novel has a number of major themes, including "problems of ethical ambiguity", and attempts to comment seriously on terrorist activity as profiled by American union struggles. Critics have shown how the American union struggles deal with similar issues in the contemporary political situation in Ireland.

Born in 1859, Arthur Conan Doyle is the author most famous for creating the detective Sherlock Holmes and is renowned as the world's greatest crime fiction writer. Spending his childhood in Scotland, his first career choice was to be a doctor, and indeed he ended up with his own medical practice. It was during the failure of this first business venture that Doyle began writing to pass the time. With the creation of Sherlock Holmes, Doyle embarked on a series of crime stories that brought new levels of realism to a marginalized genre. He also became a real-life detective on occasion, personally investigating two crimes that eventually led to the release of the accused men. His Sherlock Holmes stories have found enduring popularity and have seen countless Television, Stage, and film adaptations over the course of the last century.