The Sign of Four was the second novel featuring which famous fictional detective, following A Study In Scarlet?
Arthur Conan Doyle Sir Arthur Ignatius Conan Doyle KStJ, DL (22 May 1859 – 7 July 1930) was a British writer best known for his detective fiction featuring the character Sherlock Holmes. Originally a physician, in 1887 he published "A Study in Scarlet", the first of four novels about Holmes and Dr. Watson. In addition, Doyle wrote over fifty short stories featuring the famous detective.
The Judas Window The Judas Window (also published as "The Crossbow Murder") is a famous locked room mystery novel by the American writer John Dickson Carr (1906–1977), writing under the name of Carter Dickson, published in 1938 and featuring detective Sir Henry Merrivale.