He stepped back across the floor and was gone.  One glimpse I had of him, silhouetted against the faint light of the open door, then the door was gently closed, and I was left alone in the empty house.

Smith’s methods frequently surprised me, but always in the past I had found that they were dictated by sound reasons.  I had no doubt that an emergency unknown to me dictated his present course, but it was with my mind in a wildly confused condition, that I groped for and found the door with the broken panel and that I stood there in the complete darkness of the deserted house listening.

I can well appreciate how the blind develop an unusually keen sense of hearing; for there, in the blackness, which (at first) was entirely unrelieved by any speck of light, I became aware of the fact, by dint of tense listening, that Smith was retiring by means of some gateway at the upper end of the little garden, and I became aware of the fact that a lane or court, with which this gateway communicated, gave access to the main road.

Faintly, I heard our discharged cab backing out from the cul de sac; then, from some nearer place, came Smith’s voice speaking loudly.

“Come along, Petrie!” he cried; “there is no occasion for us to wait.  Weymouth will see the note pinned on the door.”

I started—­and was about to stumble back across the room, when, as my mind began to work more clearly, I realized that the words had been spoken as a ruse—­a favorite device of Nayland Smith’s.

Rigidly I stood there, and continued to listen.

“All right, cabman!” came more distantly now; “back to the New Louvre—­ jump in, Petrie!”

The cab went rattling away ... as a faint light became perceptible in the room beyond the broken panel.

Hitherto I had been able to detect the presence of this panel only by my sense of touch and by means of a faint draught which blew through it; now it suddenly became clearly perceptible.  I found myself looking into what was evidently the principal room of the house—­a dreary apartment with tatters of paper hanging from the walls and litter of all sorts lying about upon the floor and in the rusty fireplace.

Some one had partly raised the front window and opened the shutters.  A patch of moonlight shone down upon the floor immediately below my hiding-place and furthermore enabled me vaguely to discern the disorder of the room.

A bulky figure showed silhouetted against the dirty panes.  It was that of a man who, leaning upon the window sill, was peering intently in.  Silently he had approached, and silently had raised the sash and opened the shutters.

For thirty seconds or more he stood so, moving his head from right to left ... and I watched him through the broken panel, almost holding my breath with suspense.  Then, fully raising the window, the man stepped into the room, and, first reclosing the shutters, suddenly flashed the light of an electric lamp all about the place.  I was enabled to discern him more clearly, this mysterious spy who had tracked us from the moment that we had left the hotel.