possible."
And so they did. Hewitt's reading of the case was correct to a tittle, as it turned out, and with very little delay Samuel was released. But with the message from the police station, the fat was in the fire as regarded Lady H – . Her husband necessarily became acquainted with everything, and there was serious domestic trouble.
Samuel was glad enough to get quit of the business with no worse than a bad fright, as may well be supposed. He showed himself most grateful to Hewitt in after times, giving him excellent confidential advice and information more than once in matters connected with the diamond trade. He is still in business, I believe, in a much larger way, and I have no doubt he is the wiser for his experience, and for the lesson which Hewitt did not forget to rub well in: that it is useless and worse to place a confidential matter in the hands of a man of Hewitt's profession, and at the same time withhold particulars of the case, however unessential they may appear to be.
But meantime, on the way to Vine Street I asked Hewitt what led him to suppose that the new key on Denson's bunch fitted a lock in that particular office building.
"Call it a lucky guess, if you like," Hewitt answered; "but as a matter of fact it was prompted by pure common sense. Plummer showed me the things found on the body, and I saw at once that the keys offered the only chance of immediate information. I went through them one by one. There was his latchkey – the key with which he had gone into his lodgings to fetch away the disguise. There was another largish key, equally old – probably the key of his office door. There were other smaller keys, also old – plainly belonging to bags and trunks and drawers and so forth. And then there was the large, perfectly new key. What was that? It was not the key of any bag or drawer, clearly – it was the key of a door – a door with a lever lock. What door? Had Denson some other office? Perhaps he had, but first it was best to begin by trying it on places we were already acquainted with. At once I thought of Denson's disappearance unobserved by the housekeeper. Could this be the key of some private exit from the office building? I resolved to test that conjecture first, and it turned out to be the right one. Being successful so far, of course I turned to the other new key and tried that, as you saw."
"But what of that triangular mark on the man's forehead?"
Martin Hewitt became deeply thoughtful. "That," he said, "is a matter wholly beyond me at present, as indeed is the whole business of the murder. Whether we shall ever know more I can't guess, but the matter is deep – deep and difficult and dark. As to the mark itself, that seems to have been impressed from an engraved stamp of some sort. It is a plain equilateral triangle in red outline, measuring about an inch on each side. It is in a greasy, sticky sort of red ink, which may be smeared, but is very difficult, if not impossible, to rub away. What it means I can't at present conjecture. I have told you my reasons for not thinking it the sign of any gang of criminals. But whose sign is it? Surely not that of some self-constituted punisher of crime? For such a person, with no risk to himself, could have handed Denson over to the police, if he knew of his offence. Can he have been murdered by an accomplice? But he used no accomplice; if one thing is plain in all that story of the stolen diamonds it is that Denson did the thing wholly by himself. Besides, an accomplice would have taken the keys and have gone and secured the diamonds for himself; else why the murder at all? But no keys were taken – nothing was taken, as far as we can tell. And why was the body placed in that conspicuous position? It is pretty certain that the crime cannot have happened where the body was found – somebody must have heard or seen a struggle in such a place as that. As it is, I should say, the body was probably brought quietly to the spot in a cab, or some such conveyance.
"But mystery envelops this crime everywhere. So far as I can see, there is no clue whatever beyond the Red Triangle, which, as yet, I cannot understand. The strangling points to the murder being committed by a powerful man, certainly, and it is a form of crime that may have been perpetrated silently. But beyond that I can see nothing. The apparent motivelessness of the thing makes the mystery all the darker, and the circumstances we are acquainted with, instead of helping us, seem to complicate the puzzle.
"What was it that Denson feared when he left those diamonds behind him, when he might have carried them away? And why should he fear it in daytime and not at night, since it would seem plain that he meant to have returned for the stones at night? Where did he go to disguise himself yesterday – we know it was not in his lodgings – and where has he left the clothes he discarded?"
All these doubts and mysteries were destined to be cleared up, in more or less degree; but it was not till Hewitt and I had witnessed other singular adventures that the answer came to the problem, the real meaning of the Red Triangle was made apparent, and its connection with the theft of Samuel's diamonds grew clear. For indeed the connection proved in the end to be very intimate indeed. Once, a little later, we were allowed to see a shade farther into the mystery, as I shall tell in the proper place; but even then the real secret remained hidden from us till the appointed end.
So ended the case of Samuel's diamonds, so far as concerned Samuel himself and the owner; but the case of the Red Triangle had only begun.
THE CASE OF MR. JACOB MASON
I
The mystery of Denson's death remained a mystery, despite all the police could do. The coroner's jury returned a verdict of "Murder by some person or persons unknown" – which, indeed, was all that could be expected of them; for they had no more before them than the bare fact that the body, disguised in the clothes of a labourer, had been found on the steps near the Duke of York's column, just before midnight, by a police constable. But for the housekeeper's identification, even the name of the victim would have been unknown. The jury certainly wasted some time in idle speculation as to the strange triangular mark found on the forehead, without a speck of evidence to help them; but in the end they returned their verdict, and went home.
But the police knew a little more than the jury, though that little rather confused than helped them. They exercised their judgment at the inquest in withholding all evidence of the theft of diamonds on which the victim had been engaged, the curious particulars of which I have already related. In this they followed their usual course in cases where the evidence withheld could give the jury no help in arriving at their verdict, and at the same time might easily hamper further investigations if revealed. For the theft had been frustrated by Martin Hewitt's exertions, as we have seen, and in any case the thief was now dead and beyond the reach of human punishment. The one matter now remaining for the police was inquiry into the murder of this same thief, and the one object of their exertions the apprehension of the murderer or murderers.
The case, as I have already said, was in the hands of Inspector Plummer, an intelligent officer and an old friend of Hewitt's. A few days' work after the inquest yielded Plummer so little result that he called at Hewitt's office to talk matters over.
"I suppose," Plummer began, "it's no use asking if you've heard anything more of that matter of Denson's murder?"
Hewitt shook his head. "I haven't heard a word," he said. "If I had, it would have come on to you at once. But I hope you've had some luck yourself?"
"Not a scrap; time wasted; and the few off-chance clues I tried have led nowhere, so that I'm where I was at the start. The thing is quite the oddest in all my experience. See how we stand. Here's a man, Denson, who has just pulled off one of the cleverest jewel robberies ever attempted. He so arranges it that he walks safely off with fifteen thousand pounds' worth of diamonds, leaving the victim, Samuel, stuck patiently in an office for an hour or two before he even begins to suspect anything is wrong, and then unable to set the police after him, for the reasons you discovered. But this Denson doesn't carry the plunder off straightway, as he so easily might have done – he conceals it in the very house where the robbery was committed, taking with him a key by aid of which he may return and get it. Why? As you explained, it was probably because he feared somebody – feared being stopped and searched on the day of the robbery– not after, since it was plain he meant to return for his booty at night. Who could this have been, and why did Denson fear him? Mystery number one. Then this Denson is found dead that same night disguised in the clothes of a labourer, in a most conspicuous spot in London – the last place in the world one would expect a murderer to select for depositing his victim's body, for it is evidently not