Wheezing, the doctor took out his pipe and tobacco pouch with an air of gentle protest. Morley Standish, who had been staring out of the window, turned suddenly.
"Hold on, sir! I don't follow that. Even if Depping didn't let the man in, he might have got the key out of the pantry and put it in the door so that he could let the visitor out afterwards."
"Quite so," agreed Dr. Fell. "Then why isn't the key
there now?" "Why isn't-?"
"H’mf, yes. It's not very complicated, is it?" the other asked anxiously. "If you're a murderer leaving a room in comparative haste, throwing the door open and ducking out, does it generally occur to you to pinch the key on your way out? Why should you? If you wanted to lock the door behind you, I could understand the position. Lock the door; chuck away the key. But why, if you intend leaving the door ajar, do you want a dangerous souvenir like that?"
He lit the dregs of his pipe.
"But let's not consider that just yet. Let's tear some more flimsy shreds out of the situation as it seems. If we come back to that problem of the mummery round the entrance of Depping's visitor, I think we shall see it isn't sensible either way. If for some reason the thing were an abstruse piece of deception, with all details arranged between them beforehand, look at the fantastic nature of one of the details! I refer, gentlemen, to Depping's apparent means of putting out the lights. I can think offhand of several easy and perfecdy safe means of short-circuiting 'em. _. But what, apparendy, does Depping do? He picks up an all-steel buttonhook and shoves it into a live socket—!
"There's the buttonhook. Will any of you volunteer to do it now?"
Morley ran a hand through his sleek dark hair.
"Look here!" he protested plaintively, "I mean to say, come to think of it, if you tried that you'd get a shock that would lay you out for fifteen minutes… "
"If not considerably worse. Quite so."
Hugh Donovan found his voice for the first time. His father had ceased to be formidable now. He said: "I thought you'd just proved, doctor, that the buttonhook was used. And yet anybody would know better than to do a thing like that."
"Oh, it was used right enough; look at it. But go a step further. Can you think of any means by which it could have been used in perfect safety?"
"I confess I scarcely follow you," replied the bishop. "I cannot conjecture that it was in some fashion propped up so that it would fall into the socket at the required moment…"
"No. But what about rubber gloves?" inquired Dr. Fell.
There was a pause.
"H’mf. I'm only theorizing now, of course," the doctor rumbled, "yet, when you ally it with a few other points I shall indicate in a moment, it is an alluring theory. That's the only way the trick could have been worked. Yet again the total adds up to foolishness if we conceive that — as a part of this intricate design— Depping provided himself with a pair of rubber gloves to put out his own lights, when (as I have insisted) other and simpler methods were at hand… Nevertheless, there is another connotation of rubber gloves. If a man desires to leave no fingerprints, and yet have a free and delicate use of his hands, rubber gloves are the best sort of protection."
The bishop made a massive gesture. "My dear Dr. Fell," he intoned, almost sepulchrally, "you are getting into the realm of fantastic nonsense. Why should the late Mr. Depping have cared whether or not he left fingerprints in his own study?"
Letting out a gust of smoke, Dr. Fell leaned forward with a sort of fierce intensity and pointed his pipestem. His wheezing breath grew louder. He said:
"Exactly! Why should he? There's another, Why should he for this incredible collection. Why should he at least not make a pretense of wondering why the lights went out? Why didn't he play his part like an artist, and come out of his room to ask Storer what was wrong? Why didn't he show himself? Why did he help the visitor burn his clothes? — And last of all," said the doctor, lifting his stick and jabbing it towards the dinner tray, "why did he sample everything on that tray except his favorite soup?"
"I say, this bears a curious resemblance to the classic history of the three bears. 'Who's been sitting in my chair? Who's been drinking my porridge? Who—' Gentlemen, I think you are beginning to perceive by this time that the man in this room was not Depping at all."
The bishop muttered something to himself. A sudden dazzling suspicion seemed to make him wheel round and look at the smirking face of the dead man…
"Then Depping—" he said. "Where was Depping all this time?"
"Why, I’ll tell you " responded the doctor, and made a hideous pantomime face by way of emphasis. "He was decked out in an eye-splitting check suit, bogus jewellery, a wig, a false moustache, and actor's cement behind his ears to make them protrude. He was ringing his own doorbell and paying a call in his own house… There it is, you see. In this masquerade the roles were simply reversed, and that's what I meant by saying we should have to tear apart the facts as they seemed, or we should never understand the truth. It was X, the mysterious stranger, who posed as Depping in this room. And it was Depping — eh?"
"Can you—" said Morley Standish, "can you prove this?" He was breathing hard, and his heavy dark face, with its absurd-looking moustache, had a sudden look of relief.
"I rather think I can," said Dr. Fell modestly.
"But — ah," observed the bishop, "I — that is, I am bound to remark that this fresh approach would seem to make the matter quite as complicated and incomprehensible as it was before."
"Eh? No. No, I don't agree. Give me this reversal of roles," urged Dr. Fell, with a persuasive air, "and I undertake to simplify it. Heh. Yes."
"I can understand," pursued the other, "how Depping's appearance could have deceived Storer with only one candle burning. The very clothes alone would have had the effect of distracting his eye much as a conjuror does; which is — ah — the first principle of disguise, and, I am told, the only really effective one." It was a struggle for the bishop to include that "I am told"; but he did it. He brooded. "I can even understand the change of voice, allied to the American accent… But there is a more difficult imposture to account for. How do you account for the voice of the man in this room, imitating Depping's? Surely Storer would have known it was not the same?"
The doctor chuckled, and spilled ashes down his waistcoat.
"He would," the doctor agreed, "if he had heard it anywhere else but through a speaking tube." He pointed to the wall. "Of all the ghostly and disembodied effects in the way of communication, commend me to the speaking tube. You yourself would sound like a spirit-voice. Have you never used one? — It isn't like a telephone, you know. Go downstairs, and let each of us speak to you in turn; and I will defy you to identify your own son.
"And, you see, it was only over the speaking tube that the bogus Depping spoke to Storer. The Visitor' went upstairs, entered this room, and the door closed. Afterwards, of course, the real Depping spoke, and there was no deception to puzzle our observant valet."