Two well loved patrons of the community meet mysterious deaths in Victorian London. One is found in thousands of pieces, the other is blown up in an explosion that nearly kills Doctor Watson.
Sherlock is determined to find out what the connection between the two deaths is. He and Watson must seek out who committed the foul deeds before more innocent people are destroyed. The only clue they have is a note that mentions "The Hall of Darkness."
Based on that clue they must find out how the mysterious criminal thinks before they can proceed further. And the path to that knowledge could mean them discovering something equally as hideous as the nature of the crimes committed.