Sherlock Holmes and his nemesis Professor Moriarty are presumed dead after the fall at Reichenbach Falls. In the aftermath, a power vacuum emerges in London’s criminal underworld. Into this void steps a shadowy new mastermind. Pinkerton agent Frederick Chase arrives from New York, teaming up with Inspector Athelney Jones, a disciple of Holmes’s investigative methods. Together they must unravel the identity of this chilling figure bent on murder and mayhem — and try to restore order before chaos claims the city.