Lord Blackfield, a member of the House of Lords and a powerful critic of the Bank of England, meets a violent end in the garden of his estate. The murder weapon is the same one that was recently used to attack Irene Adler - a Kreuzberg slingshot. The evidence points to the powerful Chief Cashier of the bank, Sir John Conroy, and his son Sebastian, a rejected suitor of Irene Adler. Mycroft Holmes sends Irene in as an undercover investigator into Sir John's household. There, she is to gather evidence with the help of a gramophone modified by Mr. Wu. However, when her cover is blown, not only the investigation but also Irene Adler's very life hangs by a thread.