At the farther end, it was bounded by a crossroad, and, turning along this, I found that the wall extended nearly the same distance in this direction.  There was an opening about midway—­a small opening, closed by a heavy, iron-banded door—­the servants’ entrance, I told myself.  The grounds of a row of houses facing the road beyond ran up to the wall at the back, and I could not follow it without attracting notice, but I could see that there was no break in it.  I was almost certain that the wall which closed the estate on Godfrey’s side was also unbroken.  There were, then, only the two entrances.

I walked back again to the front, and paused for a glance through the gates.  But there was nothing to be seen.  The driveway parted and curved away out of sight in either direction, and a dense mass of shrubbery opposite the gate shut off any view of the grounds.  Even of the house, there was nothing to be seen except the chimneys and one gable.  Evidently, Mr. Vaughan was fond of privacy, and had spared no pains to secure it.

Opposite the Vaughan place, a strip of woodland ran back from the road.  It was dense with undergrowth, and, I reflected, would form an admirable hiding-place.  The road itself seemed little travelled, and I judged that the main artery of traffic was the road along which the trolley ran, two blocks away.

I returned to my starting point, and assured myself that the wall on that side was indeed without a break.  Some vines had started up it here and there, but, for the most part, it loomed grey and bleak, crowned along its whole length by that threatening line of broken glass.  I judged it to be twelve feet high, so that, even without the glass, it would be impossible for anyone to get over it without assistance.  As I stood there looking at it, resenting the threat of that broken glass, and pondering the infirmity of character which such a threat revealed, it suddenly struck me that the upper part of the wall differed slightly from the lower part.  It was a little lighter in colour, a little newer in appearance; and, examining the wall more closely, I discovered that originally it had been only eight or nine feet high, and that the upper part had been added at a later date—­and last of all, of course, the broken glass!

As I turned back, at last, toward the house, I saw someone coming up the drive.  In a moment, I recognised Swain, and quickened my steps.

“You made good time,” I said.

“Yes, sir; I was fortunate in catching an express and not having to wait for the trolley.”

“We’d better go into the house,” I added.  “I have a message for you—­a confidential message.”

He glanced at me quickly, but followed silently, as I led the way into Godfrey’s study and carefully closed the door.

“Sit down,” I said, and I sat down myself and looked at him.