The Sign of the Four and play adaptations insure this book: The Sign of the Four was also adapted for radio by Bert Coules in 1989 as part of BBC Radio 4's complete audio Sherlock Holmes, with Clive Merrison as Holmes, Michael Williams as Watson, and featuring Brian Blessed as Jonathan Small. The Sign of the Four The Sign of the Four (1890), also called The Sign of Four, is the second novel featuring Sherlock Holmes written by Sir Arthur Conan Doyle. Doyle wrote four novels and 56 short stories featuring the fictional detective. The story is set in 1888. "The Sign of the Four"
Sherlock Holmes link between medical investigation and the detection of crime. Other inspirations have been considered. One is thought to be Francis "Tanky" Smith, a policeman and master of disguise who went on to become Leicester's first private detective. Another might be "Maximilien Heller", by French author Henry Cauvain. It is not known if Conan Doyle read "Maximilien Heller", but he was fluent in French, and in this 1871 novel (sixteen years before the first adventure of Sherlock Holmes), Henry Cauvain imagined a depressed, anti-social, polymath, cat-loving, and opium-smoking Paris-based detective. Details about Sherlock Holmes' life are scarce in Conan Doyle's stories.