Following A Study in Scarlet, The Sign of the Four was published in the February 1890 edition of Lippincott’s Monthly Magazine. As with the first novel, A Study in Scarlet, The Sign of the Four was not particularly successful upon its release. In this story set in 1888, Holmes and Watson must unravel a complex plot involving the East India Company, the Indian Rebellion of 1857, a stolen treasure, a secret pact among four convicts, and two corrupt prison guards. It fleshes out Holmes’ drug habit and introduces Watson’s future wife, Mary Morstan.