arching. 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.

"'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