Sherlock Holmes, his trusted friend, Dr. John Watson, and his older brother, Mycroft, successfully unraveled a devious assassination plot against one of Queen Victoria's family. Aided by a colorful assortment of associates, a clever trap was set to attempt to stop the gang of villains from carrying out their deadly intent. Holmes had hoped their capture would lead him a step closer to the mastermind behind all of the wide-reaching criminalities. But, dead men tell no tales, and Holmes quickly learned whoever was at the head of this sinister house was a ruthless master, who did not suffer defeat without penalty, and who made certain no one would ever get an opportunity to tell what they knew.
Meanwhile, Ormond Sacker, a friend of Holmes from their university days, insinuated himself into a group of anarchists gathered in a boisterous cabaret in Paris, and learned of another assassination planned for Germany. Racing to Berlin on the Orient Express, and with the aid of a retired French detective, C. Auguste Dupin, an Italian lothario, and a clever and fearless journalist, Sacker concocts a scheme to upend the assassination attempt, at the risk of his own life.
Moreover, Holmes is convinced the world has not heard the last of this sinister house. And his apprehensions are soon realized when threats loom large in England and on the Continent.