“Only this: that I know that that mark was not there when I examined the hall yesterday. And now, Watson, let us have a little stroll round in the sunshine.”

With a confused brain, but with a heart into which some warmth of hope was returning, I accompanied my friend in a walk round the garden. Holmes took each face of the house in turn, and examined it with great interest. He then led the way inside, and went over the whole building from basement to attic. Most of the rooms were unfurnished, but none the less Holmes inspected them all minutely. Finally, on the top corridor, which ran outside three untenanted bedrooms, he again was seized with a spasm of merriment.

“There are really some very unique features about this case, Watson,” said he. “I think it is time now that we took our friend Lestrade into our confidence. He has had his little smile at our expense, and perhaps we may do as much by him, if my reading of this problem proves to be correct. Yes, yes, I think I see how we should approach it.”