It is 1917 and the Great War has been raging for three long years. Mycroft Holmes grows suspicious of one of his agents who reports back to him from the heart of the Ottoman Empire: Constantinople. Naturally, he wants to send out a man to investigate--one who knows the area, the language, the people, and has an exemplary war service record, including a fourteen-month stint posing as a German officer at the High Command in Berlin. But Sherlock Holmes proves to be, for once, stubbornly reluctant to fulfill his older brother's request.