You must have noticed how marred the woodwork is at the edge of the carpeting on that little landing above." "In the round of the staircase ?" "Yes." Mr.Gryce did not think it worth his while to answer.

Perhaps he had not time; for leaving the valet where he was, and Miss Butterworth where she was (only she would not be left, but followed him), he made his way upstairs, and paused at the place she had mentioned, with a curious look at the floor.
"You see, it has been much trodden here," she said; at which gentle reminder of her presence he gave a start; possibly he had not heard her behind him, and after sixty years of hard service even a detective may be excused a slight nervousness.

"Now, why should it be trodden here?
There is no apparent reason why any one should shuffle to and fro in this corner.

The stair is wide, especially here, and there is no window----" Mr.Gryce, whose eye had been travelling over the wall, reached over her shoulder to one of the dozen pictures hanging at intervals from the bottom to the top of the staircase, and pulling it away from the wall, on which it hung decidedly askew, revealed a round opening through which poured a ray of blue light which could only proceed from the vault of the adjoining study.
"No window," he repeated.

"No, but an opening into the study wall which answers the same purpose.