It was at this point that my humble part in the case began, for Hewitt hurried first to my rooms.

“Brett,” he exclaimed, “are you engaged this afternoon?”

“No — nothing important.”

“Will you do me a small favour? I have a rather interesting case. I want a man watched for an hour or so, and I haven’t a soul to do it. Kerrett may be known, and I am known. Besides, there is another job for Kerrett.”

Of course, I expressed myself willing to do what I could.

“Capital,” replied Hewitt. “Come along — you like these adventures, I know, or I wouldn’t have asked you; and you know the dodges in this sort of observation. The man is one Samuel, a Jew, of 150 Hatton Garden, diamond dealer. I’ll tell you more afterwards. Kerrett and I are going into the offices next door, and I want you to wait thereabout. Presently I will come downstairs with him and he will go away. An hour or so will be enough, probably.”

I followed Hewitt downstairs. He took Kerrett with him and locked his office door. I saw them both disappear within the large new building, and I waited near a convenient postal pillar-box, prepared to seem very busy with a few old letters from my pocket until my man’s back was turned.

In a very few minutes Hewitt reappeared, this time with a man — a Jew, obviously — whom I remembered having seen already at the door of that office more than an hour before, as I had passed on the way from the bookseller’s at the corner. The man walked briskly up the street, and I, on the opposite side, did the same, a little in the rear.

He turned the corner, and at once slackened his pace and looked about him. He took a peep back along the street he had left, and then hailed a cab.

For a hundred yards or more I was obliged to trot, till I saw another cab drop its fare just ahead, and managed to secure it and give the cabman instructions to follow the cab in front, before it turned a corner. The chase was difficult, for the horse that drew me was a poor one, and half a dozen times I thought I had lost sight of the other cab altogether; but my cabman was better than his animal, and from his high perch he kept the chase in view, turning corners and picking out the cab ahead among a dozen others with surprising certainty. We went across Charing Cross Road by way of Cranborne Street, past Leicester Square, through Coventry Street and up the Quadrant and Regent Street. At Oxford Circus the Jew’s cab led us to the left, and along Oxford Street we chased it past Bond Street end. Suddenly my cab pulled up with a jerk, and the driver spoke through the trapdoor. “That fare’s getting down, sir,” he said, “at the corner o’ Duke Street.”

I thrust a half-crown up through the hole and sprang out. “‘E’s crossing the road, sir,” the cabman finally reported, and I hurried across the street accordingly.

The man I was watching was strikingly Jewish enough, and easy to distinguish in a crowd. I had almost overtaken him before he had gone a dozen yards up the northern end of Duke Street. He walked on into Manchester Square. There a small, neat brougham, with blinds drawn, was being driven slowly round the central garden. I saw Samuel walk hurriedly up to this brougham, which stopped as he approached. He stepped quickly into the carriage and shut the door behind him. The brougham resumed its slow progress, and I loitered, keeping it in view, though the blinds were drawn so close that it was impossible to guess who might be Samuel’s companion, if he had one. I think I have said that when the Jew came to the office door with Hewitt I perceived that he was a man I had seen before that day. I was now convinced that I had also seen that same brougham, at the same time; but of this presently.

The carriage made one slow circuit, and then Samuel got out and shut the door quickly again. I took the precaution of turning my back and letting him overtake and pass me on his way back through Duke Street. At the end of the street he mounted an omnibus going east, and I took another seat in the same vehicle. The rest was uninteresting. He went direct to No. 150 Hatton Garden, and there remained. I read his name on the door-post among a score of others, and after a twenty-minutes’ wait I returned to my rooms. I had no doubt that it was the meeting in the brougham that Hewitt wished reported, and I remembered his rule was never to watch a man a moment after the main object was secured.

Hewitt was out, and he did not return till after dusk. Then he came straightway to my rooms.

“Well, Brett,” he said, “what’s the report? As a matter of fact, Samuel is my client, as I shall explain presently. I don’t like spying on a client, as a rule, but I was convinced that he was keeping something back from me, and there was something odd about his whole story. But what did you see?”

I told Hewitt the tale of my pursuit as I have told it here. “I came away,” I concluded, “after it seemed that he was settled in his office for a bit. But there is another thing you should know. When he first came out with you I recognised him at once as a man I had seen at that same door a little after two o’clock — say a quarter past.”

“Yes?” answered Hewitt. “I saw him there myself a little sooner — something like two, I should say. What was he doing?”

“Well,” I replied, “he was doing pretty well what he did in Manchester Square. For as a matter of fact the brougham also was here then — just outside the next-door office. I think I might swear to that same brougham — though of course I didn’t notice it so particularly that first time.”

Hewitt whistled. “Oh!” he said. “Tell me about this. Did he get into the brougham this time?”

“Yes. He came out of the office door with a black leather case in his hand and a very scared look on his face. And he popped into the brougham, leather case, scared look and all.”

“Ho — ho!” said Hewitt, thoughtfully, and whistled again. “A black leather case, eh! Come, come, the plot thickens. And what happened? Did the carriage go off?”

“No; I saw nothing more — shouldn’t have noticed so much, in fact, if the whole thing hadn’t looked a trifle curious. Nervous, pallid Jew with a black case — as though he thought it was dynamite and might go off at any moment — closed brougham, blinds drawn, Jew skipped in and banged the door, but brougham didn’t move; and I fancied — perhaps only fancied — that I saw a woman’s black veil inside. But then I turned in here and saw no more.”

Hewitt sat thoughtfully silent for a few moments. Then he rose and said, “Come next door, and I’ll tell you how we stand. The housekeeper will let us in, and we’ll see if you can identify that black case anywhere.”

It seemed that Hewitt had by this established a good understanding with the housekeeper next door. “Nobody’s been, sir,” the man said, as he admitted us and closed the heavy doors. “Office boy not come back, nor nothing.”

We went up to Denson’s office on the third floor, the door of which the housekeeper opened; and having turned on the electric light, he left us.

“Now, is that anything like the case?” Hewitt asked, when the housekeeper was gone; and he lifted from under the table the very black case I had seen Samuel take into the brougham.

I said that I felt as sure of the case as of the brougham. And then Hewitt told me the whole tale of Samuel and his loss of fifteen thousand pounds’ worth of diamonds, just as it appears earlier in this narrative.

“Now, see here,” said Hewitt, when he had made me acquainted with his client’s tale, “there is something odd about all this. See this post-card which Samuel gave me. It is from Denson, and it makes this morning’s appointment. See! ‘Be down below at eleven sharp’ is the message. He came and he waited just two hours and a quarter, as he tells me, being certain to the time within five minutes. That brings, us to a quarter-past one — the time when he finds he is robbed; and he came downstairs in a very agitated state at a quarter-past one, as I have since ascertained. At two I pass and see him still dancing distractedly on the front steps — certainly very much like a man who has had a serious misfortune, or expects one. At a quarter-past two — that was about it, I think?” (I nodded) “At a quarter-past two you see him, still agitated, diving into the brougham with this black case in his hand; and a little afterward — after all this, mind — he tells me this story of a robbery of diamonds from that very case, and assures me that he sent for me the moment he discovered the loss — that is to say, at a quarter-past one, a positive lie — and has told nobody else. He further assures me that he has told me everything that has happened up to the moment he meets me. Then he goes away — to his office, as he tells me. But you find him posting to Manchester Square in a cab, and there once more plunging into that same mysterious closed brougham. Now why should he do that? He has seen the person in that brougham, presumably, an hour before, and there can be nothing more to communicate, except the result of his interview with me — a thing I warned him to keep to himself. It’s odd, isn’t it?”

“It is. What can be his motive?”

“I want to know his motive. I object to working for a client who deceives me — indeed, it’s unsafe. I may be making myself an accomplice in some criminal scheme. You observe that he never called for the police — a natural impulse in a robbed man. Indeed, he expressly vetoes all communication with the police.”

“Of course he gave reasons.”

“But the reasons are not good enough. I can’t stop a man leaving this country anywhere round the coast except by going to the police.”

“Can it be,” I suggested, “that Samuel and Denson are working in collusion, and have perhaps insured the stones, and now want your help to make out a case of loss?”

“Scarcely that, I think, for more than one reason. First, it isn’t a risk any insurer would take, in the circumstances. Next, the insurer would certainly want to know why the police were not informed at once. But there is more. I have not been idle this while, as you would know. I will tell you some of the things I have ascertained. To begin with, Samuel is known in Hatton Garden only as a dealer on a very small and peddling scale. A dabbler in commissions, in fact, rather than a buyer and seller of diamonds in quantities on his own account. His office is nothing but a desk in a small room he shares with two others — small dealers like himself. When I spoke to the people most likely to know, of his offering fifteen thousand pounds’ worth of diamonds on his own account, they laughed. An investment of two or three hundred pounds in stones was about his limit, they said. Now that fact offers fresh suggestions, doesn’t it?” Hewitt looked at me significantly.

“You mean,” I said after a little consideration, “that Samuel may have been entrusted with the diamonds to sell by the real owner, and has made all these arrangements with Denson to get the gems for themselves and represent them as stolen?”

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 principal 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 quantity 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 glass 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 passed 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 passing 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.