A Study in Scarlet is a detective mystery novel written by Sir Arthur Conan Doyle, introducing his new character of Sherlock Holmes, who later became one of the most famous literary detective characters. The book s title derives from a speech given by Holmes to his sidekick Doctor 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 colourless skein of life, and our duty is to unravel it, and isolate it, and expose every inch of it.