A Study in Scarlet is an 1887 detective novel written by Arthur Conan Doyle. The story marks the first appearance of Sherlock Holmes and Dr. Watson, who would become the most famous detective duo in popular fiction. The book's title derives from a speech given by Holmes, a consulting 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 ...