1910: After a deadly secret British weapon falls into the hands of Bosnian terrorists, Sherlock Holmes is hired by his brother Mycroft to recover the weapon and plans. The investigation takes him to Vienna, where he meets Irene Adler again, who is there as the leading actress in a production of Die Fledermaus. In her theater, the terrorists have provisionally hidden the stolen goods and murdered the inventor of the bomb. The Adler witnessed the murder, but can't remember anything. Since the crime, however, she has been plagued by nightmares that even Sigmund Freud cannot interpret.