The sign of four

As a dense yellow fog swirls through the streets of London, a deep melancholy has descended on Sherlock Holmes, who sits in a cocaine-induced haze at 221B Baker Street. His mood is only lifted by a visit from a beautiful but distressed young woman - Mary Morstan, whose father vanished ten years before.When a beautiful young woman is sent a letter inviting her to a sinister assignation, she immediately seeks the advice of the consulting detective Sherlock Holmes.  Four years later she began to receive an exquisite gift every year: a large, lustrous pearl. Now she has had an intriguing invitation to meet her unknown benefactor and urges Holmes and Watson to accompany her. But when Holmes and Watson attend the assignation, they embark on a dark and mysterious adventure involving a one-legged ruffian, some hidden treasure, deadly poison darts and a thrilling race along the River Thames.