Something in his tone caught my ear, and I turned to look at him. An extraordinary change had come over his face. It was writhing with inward merriment. His two eyes were shining like stars. It seemed to me that he was making desperate efforts to restrain a convulsive attack of laughter.
"Dear me! Dear me!" he said at last. "Well, now, who would have thought it? And how deceptive appearances may be, to be sure! Such a nice young man to look at! It is a lesson to us not to trust our own judgement, is it not, Lestrade?"
"Yes, some of us are a little too much inclined to be cocksure, Mr. Holmes," said Lestrade. The man's insolence was maddening, but we could not resent it.
"What a providential thing that this young man should press his right thumb against the wall in taking his hat from the peg! Such a very natural action, too, if you come to think of it." Holmes was outwardly calm, but his whole body gave a wriggle of suppressed excitement as he spoke. "By the way, Lestrade, who made this remarkable discovery?"
"It was the housekeeper, Mrs. Lexington, who drew the night constable's attention to it."
"Where was the night constable?"
"He remained on guard in the bedroom where the crime was committed, so as to see that nothing was touched."
"But why didn't the police see this mark yesterday?"
"Well, we had no particular reason to make a careful examination of the hall. Besides, it's not in a very prominent place, as you see."
"No, no, of course not. I suppose there is no doubt that the mark was there yesterday?"
Lestrade looked at Holmes as if he thought he was going out of his mind. I confess that I was myself surprised both at his hilarious manner and at his rather wild observation.
"I don't know whether you think that McFarlane came out of gaol in the dead of the night in order to strengthen the evidence against himself," said Lestrade. "I leave it to any expert in the world whether that is not the mark of his thumb."
"It is unquestionably the mark of his thumb."
"There, that's enough," said Lestrade. "I am a practical man, Mr. Holmes, and when I have got my evidence I come to my conclusions. If you have anything to say you will find me writing my report in the sitting-room."
Holmes had recovered his equanimity, though I still seemed to detect gleams of amusement in his expression.
"Dear me, this is a very sad development, Watson, is it not?" said he. "And yet there are singular points about it which hold out some hopes for our client."
"I am delighted to hear it," said I, heartily. "I was afraid it was all up with him."
"I would hardly go so far as to say that, my dear Watson. The fact is that there is one really serious flaw in this evidence to which our friend attaches so much importance."
"Indeed, Holmes! What is it?"
"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 attics. 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."
The Scotland Yard inspector was still writing in the parlour when Holmes interrupted him.
"I understood that you were writing a report of this case," said he.
"So I am."
"Don't you think it may be a little premature? I can't help thinking that your evidence is not complete."
Lestrade knew my friend too well to disregard his words. He laid down his pen and looked curiously at him.
"What do you mean, Mr. Holmes?"
"Only that there is an important witness whom you have not seen."
"Can you produce him?"
"I think I can."
"Then do so."
"I will do my best. How many constables have you?"
"There are three within call."
"Excellent!" said Holmes. "May I ask if they are all large, able-bodied men with powerful voices?"
"I have no doubt they are, though I fail to see what their voices have to do with it."
"Perhaps I can help you to see that and one or two other things as well," said Holmes. "Kindly summon your men, and I will try."
Five minutes later three policemen had assembled in the hall.
"In the outhouse you will find a considerable quantity of straw," said Holmes. "I will ask you to carry in two bundles of it. I think it will be of the greatest assistance in producing the witness whom I require. Thank you very much. I believe you have some matches in your pocket, Watson. Now, Mr. Lestrade, I will ask you all to accompany me to the top landing."
As I have said, there was a broad corridor there, which ran outside three empty bedrooms. At one end of the corridor we were all marshalled by Sherlock Holmes, the constables grinning and Lestrade staring at my friend with amazement, expectation, and derision chasing each other across his features. Holmes stood before us with the air of a conjurer who is performing a trick.
"Would you kindly send one of your constables for two buckets of water? Put the straw on the floor here, free from the wall on either side. Now I think that we are all ready."
Lestrade's face had begun to grow red and angry.
"I don't know whether you are playing a game with us, Mr. Sherlock Holmes," said he. "If you know anything, you can surely say it without all this tomfoolery."
"I assure you, my good Lestrade, that I have an excellent reason for everything that I do. You may possibly remember that you chaffed me a little some hours ago, when the sun seemed on your side of the hedge, so you must not grudge me a little pomp and ceremony now. Might I ask you, Watson, to open that window, and then to put a match to the edge of the straw?"
I did so, and, driven by the draught, a coil of grey smoke swirled down the corridor, while the dry straw crackled and flamed.
"Now we must see if we can find this witness for you, Lestrade. Might I ask you all to join in the cry of 'Fire!'? Now, then; one, two, three—"
"Fire!" we all yelled.
"Thank you. I will trouble you once again."
"Fire!"
"Just once more, gentlemen, and all together."
"Fire!" The shout must have rung over Norwood.
It had hardly died away when an amazing thing happened. A door suddenly flew open out of what appeared to be solid wall at the end of the corridor, and a little, wizened man darted out of it, like a rabbit out of its burrow.
"Capital!" said Holmes, calmly. "Watson, a bucket of water over the straw. That will do! Lestrade, allow me to present you with your principal missing witness, Mr. Jonas Oldacre."
The detective stared at the new-comer with blank amazement. The latter was blinking in the bright light of the corridor, and peering at us and at the smouldering