"'Doctor Alwyn?' asked one of the men, the burliest of the three, advancing into the hall. 'I want you to come out into the country with me on a hurry call. It's a matter of life and death, and there's five thousand dollars in it for you, but the conditions attached to it are somewhat unusual. May we come into your office, and talk it over?' "I led the way, and listened to their proposition. Briefly, it was this: a young man had fallen and injured his head, and was lying unconscious in a sanitarium in the suburbs. There were reasons which could not be explained to me, why the utmost secrecy must be maintained, not only concerning the young man's identity, but the location of the retreat where he was in seclusion. They feared that he had suffered a concussion of the brain, possibly a fractured skull, and my diagnosis was required. Also, should I deem an operation necessary, I must be prepared to perform it at once. They would take me to the patient in the car, but when we reached our destination, I was to be blindfolded, and led to the sickroom, where the bandage would be removed from my eyes. I was to return in the same manner. For this service, and of course my secrecy, they offered me five thousand dollars. "Although that would not have been an exorbitant sum for me to obtain for such an operation in the days of my activities, it looked very large to me now, especially since some South American securities in which I invested had declined, but I did not feel that it would be compatible with my dignity and standing to accept the conditions which were imposed. I was, therefore, upon the point of indignantly declining, when I suddenly remembered your letter, and resolved to see the affair through. "It occurred to me, while I was selecting the instruments to take with me, that it would not be a bad idea to take also my latest camera, and if possible obtain a photograph of the patient to show you. I managed to slip it into my vest pocket, unobserved by my visitors. Here it is." Dr. Alwyn took the instrument case upon his knee and opening it, produced what looked like a large old-fashioned nickel-plated watch of the turnip variety. The doctor extended it almost apologetically. "You see," he observed, "it is really more a toy than a real camera, although it served admirably last night. I have had a great deal of amusement with it, pretending to feel people's pulses, but in reality snapping their photographs. It takes very small, imperfect pictures, of course, as you can see from the print there on your desk, and only one to each loading, but it can be carried in the palm of one's hand, and it uses a peculiarly sensitive plate that will register a snap-shot even by electric light. It had fortunately just been reloaded before the advent of my mysterious visitors, and I resolved to make use of it if an opportunity offered.