A Study in Scarlet (1887) marks the first appearance of Sherlock Holmes and Dr. Watson, who would become two of the most famous characters in popular fiction. The book's title derives from a speech given by Holmes, an amateur detective, to his friend and chronicler Watson on the nature of his work, in which he describes the story's murder investigation as his 'study in scarlet': 'There's the scarlet thread of murder running through the colorless skein of life, and our duty is to unravel it, and isolate it, and expose every inch of it.' Although Conan Doyle wrote 56 short stories featuring Holmes, A Study in Scarlet is one of only four full-length novels in the original collection.