e circumstances served only to make the case
more complex. In the first place, no reason could be given why the
young man should have fastened the door upon the inside. There was the
possibility that the murderer had done this and had afterwards escaped
by the window. The drop was at least twenty feet, however, and a bed of
crocuses in full bloom lay beneath. Neither the flowers nor the earth
showed any sign of having been disturbed, nor were there any marks
upon the narrow strip of grass which separated the house from the road.
Apparently, therefore, it was the young man himself who had fastened the
door. But how did he come by his death? No one could have climbed up to
the window without leaving traces. Suppose a man had fired through the
window, it would indeed be a remarkable shot who could with a
revolver inflict so deadly a wound. Again, Park Lane is a frequented
thoroughfare, and there is a cab-stand within a hundred yards of the
house. No one had heard a shot. And yet there was the dead man, and
there the revolver bullet, which had mushroomed out, as soft-nosed
bullets will, and so inflicted a wound which must have caused
instantaneous death. Such were the circumstances of the Park Lane
Mystery, which were further complicated by entire absence of motive,
since, as I have said, young Adair was not known to have any enemy, and
no attempt had been made to remove the money or valuables in the room.

All day I turned these facts over in my mind, endeavouring to hit upon
some theory which could reconcile them all, and to find that line
of least resistance which my poor friend had declared to be the
starting-point of every investigation. I confess that I made little
progress. In the evening I strolled across the Park, and found myself
about six o'clock at the Oxford Street end of Park Lane. A group of
loafers upon the pavements, all staring up at a particular window,
directed me to the house which I had come to see. A tall, thin man with
coloured glasses, whom I strongly suspected of being a plain-clothes
detective, was pointing out some theory of his own, while the others
crowded round to listen to what he said. I got as near him as I could,
but his observations seemed to me to be absurd, so I withdrew again in
some disgust. As I did so I struck against an elderly deformed man,
who had been behind me, and I knocked down several books which he was
carrying. I remember that as I picked them up I observed the title of
on