efficient ally. Could you scale that wall, doctor?"

I looked out of the open window. The moon still shone brightly
on that angle of the house. We were a good sixty feet from the
round, and, look where I would, I could see no foothold, nor as
much as a crevice in the brick-work.

"It is absolutely impossible," I answered.

"Without aid it is so. But suppose you had a friend up here who
lowered you this good stout rope which I see in the corner,
securing one end of it to this great hook in the wall. Then, I
think, if you were an active man, You might swarm up, wooden leg
and all. You would depart, of course, in the same fashion, and
your ally would draw up the rope, untie it from the hook, shut
the window, snib it on the inside, and get away in the way that
he originally came. As a minor point it may be noted," he
continued, fingering the rope, "that our wooden-legged friend,
though a fair climber, was not a professional sailor. His hands
were far from horny. My lens discloses more than one blood-mark,
especially towards the end of the rope, from which I gather that
he slipped down with such velocity that he took the skin off his
hand."

"This is all very well," said I, "but the thing becomes more
unintelligible than ever. How about this mysterious ally? How
came he into the room?"

"Yes, the ally!" repeated Holmes, pensively. "There are features
of interest about this ally. He lifts the case from the regions