Hewitt nodded thoughtfully. "There's that possibility," he said. "Though even in that case the owner would certainly want to know why the police had not been told, and I don't know what satisfactory answer Samuel could make. And more, I find that no such robbery has been reported to any of the princ.i.p.al dealers in Hatton Garden to-day; and, so far as I can ascertain, none of them has entrusted Samuel with anything like so large a quant.i.ty of diamonds as he talks of-lately, at any rate."

"Isn't it possible that the diamonds are purely imaginary?" I suggested. "Mightn't there be some trick played on that basis? Perhaps a trick on the American customer-if there was one."

Hewitt was thoughtful. "There are many possibilities," he said, "which I must consider. The diamonds may even be stolen property to begin with; that would account for a great deal, though perhaps not all. But the whole thing is so oddly suspicious, that unless my client is willing to let me a great deal further into his confidence to-morrow morning I shall throw up the case."

"Did you direct any inquiries after Denson?"

"Of course; which brings me to the other things I have ascertained. He has not been here long-a few months. I cannot find that he has been doing any particular business all the time with anybody except Samuel. With him, however, he seems to have been very friendly. The housekeeper speaks of them as being 'very thick together.' The rooms are cheaply furnished, as you see. And here is another thing to consider. The housekeeper vows that he never left his gla.s.s box at the foot of the stairs from the time Samuel went upstairs first to the time when he came down again, vastly agitated, at a quarter-past one, and sent a message; and during all that time Denson never pa.s.sed the box! And the main door is the only way out."

"But wasn't he there at all?"

"Yes, he was there, certainly, when Samuel came. But note, now. Observe the sequence of things as we know them now. First, there is Denson in his office; I can find nothing of any American visitor, and I am convinced that he is a total fiction, either of Denson's or Samuel and Denson together. Denson is in his office. To him comes Samuel. Neither leaves the place till Samuel comes down at a quarter-past one o'clock. I told you he sent some sort of message. The housekeeper tells me that he called a pa.s.sing commissionaire and gave him something, though whether it was a telegram or a note he did not see; nor does he know the commissionaire, nor his number-though he could easily be found if it became necessary, no doubt. Samuel sends the message, and waits on the steps, watching, in an agitated manner (as would be natural, perhaps, in a man engaged in an anxious and ticklish piece of illegality) for an hour, when this mysterious brougham appears. He takes this black case into the brougham, and he obviously brings it out again, for here it is. Whatever has happened, he brings it out empty. Then he sends the housekeeper for me. When at length I arrive, Denson has certainly gone, but there was an opportunity for that while the housekeeper was absent on the message to my office-after all Samuel's agitation, and after he had carried his case to and from the brougham."

"The whole thing is odd enough, certainly, and suspicious enough. Have you found anything else?"

"Yes. Denson lives, or lived, in a boarding house in Bloomsbury. He has only been there two months, however, and they know practically nothing of him. To-day he came home at an unusual time, letting himself in with his latchkey, and went away at once with a bag, but the accounts of the exact time are contradictory. One servant thought it was before twelve, and another insisted that it was after one. He has not been back."

"And the office boy-can't you get some information out of him?"

"He hasn't been seen since the morning. I expect Denson told him to take a whole holiday. I can't find where he lives, at the moment, but no doubt he will turn up to-morrow. Not that I expect to get much from him. But I shan't bother. Unless Mr. Samuel will answer satisfactorily some very plain questions I shall ask-and I don't expect he will-I shall throw up the commission. He called, by the way, not long ago, but I was out. We shall see him in the morning, I expect."

A look round Denson's office taught me no more than it had taught Hewitt already. There were two small rooms, one inside the other, with ordinary and cheap office furniture. It was quite plain that any man of ordinary activity and size could have got out of the inner room into the corridor by the means which Samuel suggested-through the hinged wall-light, near the ceiling. Hewitt had meddled with nothing-he would do no more till he was satisfied of the bona fides of his client; certainly he would not commit himself to breaking open desks or cupboards. And so, the time for my attendance at the office approaching-I was working on the Morning Ph[oe]nix then, and ten at night saw my work begin-we shut Denson's office, and went away.

III

In the morning I was awakened by an impatient knocking at my bedroom door. Going to bed at two or three I was naturally a late riser, and this was about nine. I scrambled sleepily out of bed, and turned the key. Hewitt was standing in my sitting-room, with a newspaper in his hand.

"Sorry to break your morning sleep, Brett," he said, "but something interesting has happened in regard to that business you helped me with yesterday, and you may like to know. Crawl back into bed if you like."

But I was already in my dressing-gown, and groping for my clothes. "No, no, come in and tell me," I said. "What is it?"

Hewitt sat on the bed. "I'll tell you in due order," he said. "First, I saw Samuel again last night-after you had gone away. You remember I went back to my office; I had a letter or two to write which I had set aside in the afternoon. Well, I wrote the letters, shut up, and went downstairs. I opened the outer door, and there was Samuel, in the act of ringing the housekeeper's bell. He said he was very anxious, and couldn't sleep without coming to hear if I had made any progress; he had called before, but I was out. I half thought of taking him back to my office, but decided that it wasn't worth while. So I walked along to the corner of the Strand, till I got him well under the lights. Then I stopped and talked to him. 'You ask about the progress in your case, Mr. Samuel,' I said. 'Now, I have sometimes met people who seem to consider me a sort of prophet, seer, or diviner. As a matter of fact, I am nothing but a professional investigator, and even if I were possessed of such an amazing genius as I lay no claim to, I could never succeed in a case, nor even make progress in it, if my client started me with false information, or only told me half the truth. More, when I find that such is the state of affairs, and that if I am to succeed I must begin by investigating my client before I proceed with his case, I throw that case up on the instant-invariably. Do you understand that? Now I must tell you that I have made no progress with your case, none; for that very reason.'"

"He protested, of course-vowed he had told me the simple truth, and so forth. I replied by asking him certain definite questions. First, I asked him whose the diamonds were. He repeated that they were his own. To that I simply replied, 'Good evening, Mr. Samuel,' and turned away. He came after me beseechingly, and prevaricated. He said something about another party having an interest, but the matter being confidential. To that I responded by asking him with whom he had communicated before sending for me, and who was the person in the brougham which he had twice entered. That flabbergasted him. He said that he couldn't answer those questions without bringing other parties into the matter, to which I answered that it was just those other parties that I meant to know about, if I were to move a step in the matter. At this he got into a sad state-imploring, actually imploring, me not to desert him. He said he should do something desperate-something terrible-that night if I didn't relieve his mind, and undertake the case. What he meant he'd do I didn't know, of course, but it didn't move me. I said finally that I would deal only with princ.i.p.als, and that until I had the personal instructions of the actual owner of the diamonds, in addition to a complete explanation of the brougham incident, I should do nothing, and I recommended him to go to the police; and with that I left him."

"And you got nothing more from him than that?"

"Nothing more; but it was something, you see. He admitted, to all intents, that the diamonds were not his own. And now see here. I suppose I left him about ten o'clock. Here is a paragraph in one of this morning's newspapers. It is only in the one paper; the matter seems to have occurred rather late for press."

Hewitt gave me the paper in his hand, pointing to the following paragraph:

"Horrible Discovery.-A shocking discovery was made just before midnight last night, near the York column, where a police-constable found the dead body of a man lying on the stone steps. The body, which was fully clothed in the ordinary dress of a labouring man, bore plain marks of strangulation, and it was evident that a brutal murder had been committed. A singular circ.u.mstance was the presence of a curious reddish mark upon the forehead, at first taken for a wound, but soon discovered to be a mark apparently drawn or impressed on the skin. At the time of going to press, no arrest had been made, and so far the affair appears a mystery."

"Well," I said, "this certainly seems curious, especially in the matter of the mark on the forehead. But what has it all to do--"

"To do with Samuel and his diamonds, you mean? I'll tell you. That dead man is Denson!"

"Denson?" I exclaimed. "Denson? How?"

"I get it from the housekeeper next door. It seems that when the police came to examine the body they found, among other things-money and a watch, and the like-a piece of an addressed envelope, used to hold a few pins-the pins stuck in and the paper rolled up, you know. There was just enough of it to guess the address by-that of the office next door; and it was the only clue they had. So they came along here at once and knocked up the housekeeper. He went with them and instantly recognised Denson, disguised in labourer's clothes, but Denson, he says, unmistakably."

"And the mark on the forehead?"

"That is very odd. It is an outlined triangle, rather less than an inch along each side. It is quite red, he says, and seems to be done in a greasy, sticky sort of ink or colour."

"Was anything found-the diamonds?"

"No. He says there was money-two or three five-pound notes, I believe, some small change, a watch, keys and so forth; but there's not a word of diamonds."

I paused in my dressing. "Does that mean that the murderer has got them?" I asked. Hewitt pursed his lips and shook his head. "It may mean that," he said, "but does it look altogether like it when five-pound notes are left? On the other hand, there is the disguise; the only reason that we know of for that would be that he was bolting with the diamonds. But the really puzzling thing is the mark on the forehead. Why that? Of course, the picturesque and romantic thing to suppose is that it is the mark of some criminal club or society. But criminal a.s.sociations, such as exist, don't do silly things like that. When criminals rob and murder, they don't go leaving their tracks behind them purposely-they leave nothing that could possibly draw attention to them if they can help it; also, they don't leave five-pound notes. But I'm off to have a look at that mark. Inspector Plummer is in charge of the case-you remember Plummer, don't you, in the Stanway Cameo case, and two or three others? Well, Plummer is an old friend of mine, and not only am I interested in this matter myself, but now that it becomes a case of murder, I must tell the police all I know, merely as a loyal citizen. I've an idea they will want to ask our friend Mr. Samuel some very serious questions."

"Will you go now?"

"Yes, I must waste no more time. You get your breakfast and look out for me, or for a message."

Hewitt was off to Vine Street, and I devoted myself to my toilet and my breakfast, vastly mystified by this tragic turn in a matter already puzzling enough.

It was not a messenger, but Hewitt himself, who came back in less than an hour. "Come," he said, "Plummer is below, and we are going next door, to Denson's office. I've an idea that we may get at something at last. The police are after Samuel hot-foot. They think he should be made sure of in any case without delay; and I must say they have some reason, on the face of it."

We joined Plummer at once-I have already spoken of Plummer in my accounts of several of Hewitt's cases in which I met him-and we all turned into the office next door. There we found a very frightened and bewildered office boy, whom Denson had given a holiday yesterday, after sending him down to Samuel. He had come to his work as usual, only to meet the housekeeper's tale of the murder of his master and the end of his business prospects. He had little or no information to impart. He had only been employed for a month or six weeks, and during that time his work had been practically nothing.

Plummer nodded at this information, and sniffed comprehensively at the office furniture. "I know this sort o' stuff," he said. "This is the way they fit up long firm offices and such. This place was taken for the job, that's plain, by one or both of 'em."

The boy's address was taken, and he was given a final holiday, and asked to send up the housekeeper as he went out. Plummer pa.s.sed Hewitt a bunch of keys.

The housekeeper entered. "Now, Hutt," said Martin Hewitt, "you were saying yesterday, I think, that the main front door was the only entrance and exit for this building?"

"That's so, sir-the only one as anybody can use, except me."

"Oh! then there is another, then?"

"Well, not exactly to say an entrance, sir. There's a small private door at the back into the court behind, but that's only opened to take in coals and such, and I always have the key. This house isn't like yours, sir; you have no back way into the court as we have. It's a convenience, sometimes."

"Ah, I've no doubt. Do you happen to have the key with you?"

"It's on the bunch hanging up in my box, sir. Shall I fetch it?"

"I should like to see it, if you will."

The housekeeper disappeared, and presently returned with a large bunch of keys.

"This is the one, Mr. Hewitt," he explained, lifting it from among the rest.

Hewitt examined it closely, and then placed beside it one from the bunch Plummer had given him. "It seems you're not the only person who ever had a key exactly like that, Hutt," he said. "See here-this was found in Mr. Denson's pocket."

Plummer nodded sagaciously. "All in the plant," he said. "See-it's brand new; clean as a new pin, and file marks still on it."

"Take us to this back door, Hutt," Hewitt pursued. "We'll try this key. Is there a back staircase?"