Winter, 1890. A deep freeze has fallen upon London, and its citizens remain huddled indoors. But the cogs of the criminal underworld never stop turning, and Holmes and Watson find themselves embroiled in a crime that rocks the art world.

Sir Wellington is disturbed in the middle of the night, apprehending a thief attempting to steal his rare and valuable 14th century portrait of King Edward III. In the kerfuffle that follows, the painting is set ablaze and the thief escapes. When the police track down the criminal to take him to the station, he is fatally shot by an unknown assailant.

But the labyrinth of deceit grows even more impenetrable, as the painting's provenance is called into question and Holmes and Watson find themselves in the midst of a vast conspiracy. It seems that this incident is just one of many at the hands of a powerful crime syndicate, duping the London's wealthy into buying imitation artwork; with the renowned National Portrait Gallery supposedly at the center. With usurped identities, shootings, chases and conspiracies, Holmes and Watson find themselves enmeshed in a tangled web of theft, forgery and murder. Can the famous duo untangle the mystery and expose the criminal network before it is too late? Or will this case prove too complex for even their brilliant minds?