these two keys, and he has made copies of them. And here we come on a curious thing. It is easy enough to understand why he should foresee and get himself a key for the back door, in order to make his escape. But why the key of the hose-cupboard? Why, indeed, should he leave the diamonds behind him at all? It is plain that he meant to come back for them – probably at night. He would have been wholly free from observation in that quiet courtyard, and he could let himself in, get the diamonds, and leave again without exciting the smallest alarm or suspicion. But why take all the trouble? Why not stick to the plunder from the beginning? The plain inference is that he feared somebody or something. He feared being stopped and searched, or he feared being waylaid sometime during yesterday. By whom? There's the puzzle, and I can't see the bottom of it, I confess. If I could, perhaps I might know something of last night's murder.
"As to Samuel's prevarications, there is only one explanation that will fit, now that the rest is made clear. He must have been entrusted with these diamonds by a private owner, for sale – secretly. Some lady of conspicuous position in difficulties, probably – perhaps unknown to her husband. Such things occur every day. A common expedient is to sell the stones and have good paste substituted, in the same settings. Samuel would be just the man to carry through a transaction of that sort. That would account for everything. The jewels are en suite, cut, but unset – taken from a set of jewellery, and paste substituted. Samuel arranges it all for the lady, finds a customer – Denson – who treats him exactly as he has told us. When he realises the loss Samuel doesn't know what to do. He mustn't call the police, being bound to secrecy on the lady's behalf. He sends her a hasty message, and remains keeping watch by Denson's office. She hurries to him with all possible secrecy, keeping her carriage blinds down; he dashes into the brougham to describe the disaster, taking his case with him in his frantic desire to explain things fully. The lady fears publicity, and won't hear of the police – she instructs him to consult me: and consequently, of course, when I recommend communicating with the police he won't listen to the suggestion. Samuel has arranged with the lady to hurry off and report progress as soon as he has consulted me, and this he does, the lady having appointed Manchester Square for the interview. Perhaps she hints some suspicion of Samuel's honesty – rather natural, perhaps, in the circumstances. That terrifies him more than ever, and leads to his frantic appeals to me when I throw the case up. Come, there's my guess at the facts of the case, and I'll back it with twopence and a bit more. Eh, Plummer?"
"I don't take your bet," answered Plummer. "The thing's plain enough; except the murder. There's something deeper there."
Hewitt became grave. "That's true," he said, "and something I can see no way into, as yet. But come – you take this parcel of diamonds, as representing the law. And here comes one of your men, I think."
We had been approaching the front door during this talk, and now a police constable appeared, and saluted Plummer. "Samuel's just been brought in, sir," he reported. "He's half dead with fright, and he's sent a message to Lady H – in P – Square; and he says he wants Mr. Martin Hewitt to come and speak for him."
"Poor Samuel!" Hewitt commented. "Come, we'll go and make him happy. Here are the diamonds, and, those safely accounted for, there's no evidence to connect him with the murder. We'll get him out of the mess as soon as 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
