A missing amulet and an old enemy... After a dramatic battle with Professor James Moriarty at Reichenbach Falls, Sherlock Holmes is reported dead. The news has crushed his friend and chronicler Dr John Watson, who has taken to drink, nearly destroying his practice and health. In an attempt to restore Watson to sound mind and body, Sherlock's brother Mycroft sends him on a mysterious mission to New York state. His assignment is to thwart Moriarty's successor, Colonel Sebastian Moran, from securing a treasure mentioned in a Robert Louis Stevenson novel. But there is much more to it than that... Sherlock reappears. Along with Watson, the notorious Lillie Langtry, members of an Iroquois secret society and pair of legendary western outlaws, Holmes is drawn into a near-catastrophic clash in the cave of Mad Bear.