A Study in Scarlet, detective novel by Conan Doyle, written in 1886, the story 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 colour ...