Ashton-Kirk, a wealthy young detective who delights in solving mysteries involving ancient tablets, forgotten books, documents and treaties, is asked by Stella Morse, the secretary and niece of Dr. Morse, to investigate the origin of mysterious letters threatening the physician's life. Ashton-Kirk learns from the Secretary of State that the head of the Japanese spy network in Washington offered the dissolute son of Russian Count Drevonoff a large sum of money to steal a copy of a secret treaty conducted between Russia and the United States during the Russo-Japanese War. The count, who discovered the treaty in his son's possession, was thought to have stolen it and sent to war in disgrace. Dr. Morse, who treated the injured count at the front, unwittingly obtained the document. Although Dr. Morse is subsequently killed, Ashton-Kirk proves that the murder was accidentally committed by Nanon, the housekeeper.