Sir Arthur Conan Doyle (1859–1930) was a Scottish physician and writer known around the world for his stories about detective Sherlock Holmes, which all but created the literary field of crime fiction and made the name Sherlock Holmes synonymous with detectives. Aside from the Sherlock Holmes stories, he was a prolific writer whose other works include science fiction stories, historical novels, plays and romances, poetry, and non-fiction.

A Study in Scarlet was the first work of fiction to incorporate the magnifying glass as an investigative tool. The book's title derives from a speech given by Holmes to his companion 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."