The Sign of the FourHarperCollins is proud to present its incredible range of best loved, essential classics. How often have I said to you that when you have eliminated the impossible whatever remains, however improbable, must be the truth? In London, 1888, the razor sharp detective skills of Sherlock Holmes are to be put to the test. Mary Morstan reports two seemingly unconnected and inexplicable events: the disappearance of her father, a British Indian Army captain,