The Complete New Edition of The Sign of the Four by Sir Arthur Conan Doyle. 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 stories starring the fictional detective. The story is set in 1888. The Sign of the Four has a complex plot involving service in East India Company, India, the Indian Rebellion of 1857, a stolen treasure, and a secret pact among four convicts ("the Four" of the title) and two corrupt prison guards. It presents the detective's drug habit and humanizes him in a way that had not been done in the preceding novel A Study in Scarlet (1887). It also introduces Doctor Watson's future wife, Mary Morstan.About the Author: Sir Arthur Ignatius Conan Doyle KStJ, DL (22 May 1859 - 7 July 1930) was a Scottish physician and writer who is most noted for his fictional stories about the detective Sherlock Holmes, which are generally considered milestones in the field of crime fiction. He is also known for writing the fictional adventures of a second character he invented, Professor Challenger, and for popularising the mystery of the Mary Celeste. He was a prolific writer whose other works include fantasy and science fiction stories, plays, romances, poetry, non-fiction, and historical novels.