“Certainly, but how- -?”

He laughed at my bewildered expression.

“There is a delightful freshness about you, Watson, which makes it a pleasure to exercise any small powers which I possess at your expense. A gentleman goes forth on a showery and miry day. He returns immaculate in the evening with the gloss still on his hat and his boots. He has been a fixture therefore all day. He is not a man with intimate friends. Where, then, could he have been? Is it not obvious?”

“Well, it is rather obvious.”

“The world is full of obvious things which nobody by any chance ever observes. Where do you think that I have been?”

“A fixture also.”

“On the contrary, I have been to Devonshire.”

“In spirit?”

“Exactly. My body has remained in this armchair and has, I regret to observe, consumed in my absence two large pots of coffee and an incredible amount of tobacco. After you left I sent down to Stamford’s for the Ordnance map of this portion of the moor, and my spirit has hovered over it all day. I flatter myself that I could find my way about.”

“A large-scale map, I presume?”

“Very large.” He unrolled one section and held it over his knee. “Here you have the particular district which concerns us. That is Baskerville Hall in the middle.”

“With a wood round it?”

“Exactly. I fancy the yew alley, though not marked under that name, must stretch along this line, with the moor, as you perceive, upon the right of it. This small clump of buildings here is the hamlet of Grimpen, where our friend Dr. Mortimer has his headquarters. Within a radius of five miles there are, as you see, only a very few scattered dwellings. Here is Lafter Hall, which was mentioned in the narrative. There is a house indicated here which may be the residence of the naturalist - Stapleton, if I remember right, was his name. Here are two moorland farmhouses, High Tor and Foulmire. Then fourteen miles away the great convict prison of Princetown. Between and around these scattered points extends the desolate, lifeless moor. This, then, is the stage upon which tragedy has been played, and upon which we may help to play it again.”

“It must be a wild place.”

“Yes, the setting is a worthy one. If the devil did desire to have a hand in the affairs of men- -”

“Then you are yourself inclining to the supernatural explanation.”

“The devil’s agents may be of flesh and blood, may they not? There are two questions waiting for us at the outset. The one is whether any crime has been committed at all; the second is, what is the crime and how was it committed? Of course, if Dr. Mortimer’s surmise should be correct, and we are dealing with forces outside the ordinary laws of Nature, there is an end of our investigation. But we are bound to exhaust all other hypotheses before falling back upon this one. I think we’ll shut that window again, if you don’t mind. It is a singular thing, but I find that a concentrated atmosphere helps a concentration of thought. I have not pushed it to the length of getting into a box to think, but that is the logical outcome of my convictions. Have you turned the case over in your mind?”

“Yes, I have thought a good deal of it in the course of the day.”

“What do you make of it?”

“It is very bewildering.”

“It has certainly a character of its own. There are points of distinction about it. That change in the footprints, for example. What do you make of that?”

“Mortimer said that the man had walked on tiptoe down that portion of the alley.”

“He only repeated what some fool had said at the inquest. Why should a man walk on tiptoe down the alley?”

“What then?”