"My profession has ethics, too, Doctor, although you may not have conceived it," the detective reminded him, quietly. "Even more than doctor or priest, a professional investigator must preserve inviolate the secrets which are imparted to him, whether they take the form of a light under a bushel or a skeleton in a closet. In the cause of justice, only, may he open his lips. I hold safely locked away in my mind the keys to mysteries which, were they laid bare, would disrupt society, drag great statesmen from their pedestals, provoke international complications, even bring on wars. If you know anything pertaining to the matter of which I wrote you, justice and the ethics of your profession require you to speak." "I agree with you, sir. As I said, I am not certain that my adventure--for it was quite an adventure for a retired man like myself, I assure you--has anything to do with the case you are investigating, but we can soon establish that. Do you recognize the subject of this photograph?" The doctor drew from his pocket a small square bit of cardboard, and Blaine took it eagerly from him. One glance at it was sufficient, and it was with difficulty that the detective restrained the exclamation of triumph which rose to his lips. Upon the card was mounted a tiny, thumbnail photograph of a face--the face of Ramon Hamilton! It was more like a death-mask than a living countenance, with its rigid features and closed eyes, but the likeness was indisputable. "I recognize it, indeed, Doctor. That is the man for whom I am searching. How did it come into your possession?" "I took it myself, last night." The spare figure of the elderly physician straightened proudly in his chair. "When your communication arrived, I did not attach much importance to it because it did not occur to me for a moment that I should have been selected, from among all the physicians and surgeons of this city, for such a case. When the summons came, however, I remembered your warning--but I anticipate. Since my patient of last night is your subject, I may as well tell you my experiences from the beginning. My name is Alwyn--Doctor Horatius Alwyn--and I live at Number Twenty-six Maple Avenue. Until my retirement seven years ago I was a regular practising physician and surgeon, but since my break-down--I suffered a slight stroke--I have devoted myself to my books and my camera--always a hobby with me. "Well--late last night, the front door-bell rang. It was a little after eleven, and my wife and the maid had retired, but I was developing some plates in the dark-room, and opened the door myself. Three men stood there, but I could see scarcely anything of their faces, for the collars of their shaggy motor coats were turned up, their caps pulled low over their eyes, and all three wore goggles.