The novel begins in 1891, when Holmes first informs Watson of his belief that Professor James Moriarty is a "Napoleon of Crime". The novel presents this view as nothing more than the fevered imagining of Holmes' cocaine-sodden mind and further asserts that Moriarty was the childhood mathematics tutor of Sherlock and his brother Mycroft. Watson meets Moriarty, who denies that he is a criminal and reluctantly threatens to pursue legal action unless the latter's accusations cease. Moriarty also refers to a "great tragedy" in Holmes' childhood, but refuses to explain further when pressed by Watson.