«The sign of the four» by Sir Arthur Conan Doyle

The Sign of the Four (1890), is the second novel featuring Sherlock Holmes written by Sir Arthur Conan Doyle. 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 A Study in Scarlet.

Sir Arthur Conan Doyle described how he was commissioned to write the story over a dinner with Joseph M. Stoddart, managing editor of Lippincott's Monthly Magazine, at the Langham Hotel in London on 30 August 1889. Stoddart wanted to produce an English version of Lippincott"s with a British editor and British contributors. The dinner was also attended by Oscar Wilde, who eventually contributed The Picture of Dorian Gray to the July 1890 issue. Doyle discussed what he called this "golden evening" in his 1924 autobiography Memories and Adventures.

As with the first story, A Study in Scarlet, produced two years previously, The Sign of the Four was not particularly successful to start with. It was the short stories, published from 1891 onwards in Strand Magazine, that made household names of Sherlock Holmes and his creator.