London, 1889. In a city still reeling from the depredations of Jack the Ripper another killer arises. Stalking the West End and Marylebone and striking at a seemingly unconnected group of victims, the murderer leaves fear and confusion in his wake. Mr. Sherlock Holmes, Dr. John Watson, and Inspector Lestrade face a case like no other they have yet faced. A case that will leave each of them changed and bring personal danger as they race against a mounting death toll to bring down the Molly-Boy Murderer.