A Study in Scarlet is the first novel featuring Sherlock Holmes and Dr. John Watson, written by Arthur Conan Doyle. The story follows Watson, a military doctor, as he meets the brilliant but eccentric detective Holmes and becomes his roommate at 221B Baker Street. Together, they investigate a baffling murder in London, which leads to a deeper mystery rooted in events from the American West. The novel introduces Holmes's keen powers of deduction and forensic science, establishing him as one of literature's greatest detectives.