"A Study in Scarlet" is the first novel featuring Sherlock Holmes, written by Sir Arthur Conan Doyle and published in 1887. The book introduces the iconic characters of Sherlock Holmes and Dr. John H. Watson, who become roommates and, shortly after, close friends. The novel's narrative is centered around the investigation of a mysterious murder in London, showcasing Holmes' brilliant deductive reasoning skills. The story also features a lengthy flashback to the American West, explaining the motives behind the crime. Overall, "A Study in Scarlet" sets the stage for the Holmesian canon, blending elements of mystery, drama, and complex human emotions.