Days after Sherlock Holmes and his arch-enemy Moriarty fall to their doom at the Reichenbach Falls, Pinkerton agent Frederick Chase arrives in Europe from New York. The death of Moriarty has created a poisonous vacuum which has been swiftly filled by a fiendish new criminal mastermind who has risen to take his place. Ably assisted by Inspector Athelney Jones of Scotland Yard, a devoted student of Holmes's methods of investigation and deduction, Chase must forge a path through the darkest corners of the capital to shine a light on this shadowy figure - a man much feared but seldom seen; a man determined to engulf London in a tide of murder and menace.