One day about two weeks after the unravelling of the mystery of the opal lost on board the yacht Idler, Mr. Barnes called upon Mr. Mitchel and was cordially received.

"Glad to see you, Mr. Barnes. Anything stirring in the realm of crime?"

"'Stirring' would be a fitting adjective, I think, Mr. Mitchel. Ever since the Idler affair I have occupied myself with a study of the problem, which I am convinced we have but partially solved. You may recall that you gave me a clue."

"You mean that Livingstone, when he gave me the opal, remarked, 'Women are poor conspirators.' Yes, I remember calling your attention to that. Has your clue led to any solution?"

"Oh, I am not out of the maze yet; more likely just entering the most intricate depths. Still, I flatter myself that I have accomplished something; enough to satisfy me that 'mischief is brewing,' and that the conspirators are still conspiring. Moreover, there is little doubt that you are deeply concerned in the new plot."

"What! You insinuate that I am in this conspiracy?"

"Only as a possible victim. You are the object of the plot."

"Perhaps you think that I am in danger?" Mr. Mitchel smiled as though the idea of danger were a pleasurable one.

"Were you any other man than yourself, I should say most decidedly that you are in danger."

"But, being myself, you fancy that the danger will pass from me?"

"Being yourself, I anticipate that you will compel the danger to pass from you."

"Mr. Barnes, you flatter me. Perhaps I may be able to thwart the conspirators, now that you warn me; if I do, however, I must admit my great indebtedness to you. To be forewarned is to have the fight half won, and I candidly say that I was entirely unsuspicious of any lurking danger."

"Exactly. With all your acumen, I was sure that your suspicions had not been aroused. The conspirators are wary, and, I assure you, unusually skilful. So, under all the circumstances, I felt it my duty to be on the alert."

"Ah, I see," said Mr. Mitchel, in that tone peculiar to him, which made it doubtful whether he spoke in earnest, or whether his words hid keen satire. "The old cat being asleep, the kitten watches. That is very nice of you. Really, it is quite a comforting thought that so skilful a detective is ever guarding my person. Especially as I am the owner of so many gems to which the covetous must ever look longingly."

"That is just how I reasoned it," said Mr. Barnes, eagerly, wishing to justify his actions, which he began to suspect Mr. Mitchel might resent. "You explained to me your reasons why you have purchased so many valuable jewels. You claimed that almost every large gem has been the cause, or rather the object, of crime. The Aztec Opal came into your possession under most peculiar circumstances. In fact, you thwarted a criminal just as he had come into possession of it. But this criminal is a wealthy man. Not perhaps as rich as yourself, but rich enough to be above stealing even such a valuable bauble. It could not have been the intrinsic value of the opal which tempted him; it must have been that some special reason existed; some reason, I mean, for his acquiring possession of this particular opal. All this being true, it would be a natural sequence that his efforts to get the opal would not cease merely because it had changed hands."

"Your argument is most interesting, Mr. Barnes, especially as it is without a flaw. As you say, from all this reasoning it was a natural sequence that Mr. Livingstone would continue his quest for the opal. This being so obvious, did you imagine that it had escaped me?"

Mr. Barnes was confused by the question. He really admired Mr. Mitchel very much, and though he considered him quite conceited, he also admitted that he had great analytical powers and remarkable acumen. He also, more than anything else, desired a perpetuation of his friendship; indeed, it had been with an idea of increasing the bond between them that he had called. He had spent much of his time, time which could have been occupied with other matters to better financial advantage, and all with the purpose of warding off from his friend a danger which he had at first considered as a distant possibility, but which later he looked upon as certain, if nothing intervened to hinder the plot, which he knew was rapidly approaching the moment of execution. He therefore hastened to make further explanation:

"Not at all – not at all. I am merely indicating the steps by which I reached my conclusions. I am giving you my reasons for what I fear you now may consider my interference in your affairs. Yet I assure you I meant it all – "

"For the best. Why, of course, my friend; did you suppose that I doubted your good intent, merely because I spoke brusquely?" Mr. Mitchel held out his hand cordially, and Mr. Barnes grasped it, glad to note the altered demeanor of his companion. Mr. Mitchel continued: "Will you never learn that my weakness is for antagonizing detectives? When you come here to tell me that you have been 'investigating' my private affairs, how could I resist telling you that I knew all about it, or that I could take care of myself? I would not be Leroy Mitchel were it otherwise."

"How do you mean that you know all about it?"

"Well, perhaps not all. I am not exactly omniscient. Still, I know something. Let me see, now. How much do I know? First, then, you have had this Livingstone watched. Second, you have introduced one of your spies, a young woman, into the home of Mrs. Gray. In spite of your alleged faith in Dennett Moore, you had him watched also, though for only two or three days. Lastly, you have discovered Pedro Domingo, and – "

"In Heaven's name, Mr. Mitchel, how do you know all this?" Mr. Barnes was utterly dumbfounded by what he had heard.

"All this?" said Mr. Mitchel, with a suave smile; "why, I have mentioned only four small facts."

"Small facts?"

"Yes, quite small. Let us run them over again. First, I stated that you had Mr. Livingstone watched. That was not hard to know, because I also had a spy upon his track."

"You?"

"Yes, I. Why not? Did you not just now agree that it was obvious that he would continue his efforts to get the opal? Being determined that I should never part with it whilst alive, it likewise followed that he must kill me, or have me killed, in order to obtain it. Under these circumstances it was only common caution to have the man watched. Indeed, the method was altogether too common. It was bizarre. Still, my spy was no common spy. In that, at least, my method was unique. Secondly, I claimed that you had introduced a woman spy into the home of Mrs. Gray. To learn this was even easier. I deduced it from what I know of your methods. You played the same trick on my wife once, I think you will recall. Supposing Mrs. Gray to be a conspirator (that was your clue, I think), you would hardly watch Livingstone and neglect the woman. Yet the actual knowledge came to me in a very simple manner."

"How was that?"

"Why, Mr. Gray told me."

"Mr. Gray told you?"

"Mr. Gray himself. You see, your assistants are not all so clever as yourself, though I doubt not this girl may think that she is a genius. You told her to seek a position in the house, and what does she do? She goes straight to Mr. Gray and tells him her purpose; hints that it might be well for him to know just what really actuated Mrs. Gray in the curious affair on the yacht, and agrees to 'discover everything' – those were her words – if he would give her the opportunity. Poor man, she filled his mind with dire suspicions and he managed it so that she was taken into service. Up to the present time she has discovered nothing. At least, so she tells him."

"The little she-devil! You said that she explained her whole purpose. Do you mean – "

"Oh, no. She did not implicate you, nor divulge her true mission. The fun of the thing is that she claimed to be a 'private detective' and that this venture was entirely her own idea. In fact, she is working for Mr. Gray. Is not that droll?" Mr. Mitchel threw back his head and laughed heartily. Mr. Barnes did not quite see the fun, and looked grim. All he said was:

"She acted beyond her instructions, yet it seems that she has not done any harm; and though she is like an untamed colt, apt to take the bit between her teeth, still she is shrewd. But I'll curb her yet. Now as to your third fact. How did you know that I had Mr. Moore watched, and only for two or three days?"

"Why, I recognized one of your spies following him one day down Broadway, and as Moore sailed for Europe two days after, I made the deduction that you had withdrawn your watch-dog."

"Well, then," said Mr. Barnes, testily, "how did you know that I had, as you declare, 'discovered Pedro Domingo'?"

"How did I know that? Why – but that can wait. You certainly did not call this morning to ask me all these questions. You came, as I presume, to convey information."

"Oh, you know so much, it is evidently unnecessary for me to tell you of my trifling discoveries." Mr. Barnes was suffering from wounded pride.

"Come, come," exclaimed Mr. Mitchel, cheerily, "be a man; don't be downcast and fall into the dumps merely because I surprised a few trifling facts in your game, and could not resist the fun of guying you a little. You see, I still admit that what I know are but trifling facts; what you know, on the contrary, is perhaps of great importance. Indeed, I am assured that without your information, without a full knowledge of all that you have discovered, my own plans may go awry, and then the danger at which you hint might be all too real. Do you not see that, knowing that you are interested in this case, I have been only too willing to let half the burden of the investigation fall upon you? That to your skill I have intrusted all of that work which I knew you could do so well? That in the most literal sense we have been silent partners, and that I depended upon your friendship to bring you to me with your news, just as it has brought you?"

This speech entirely mollified Mr. Barnes, and, with a brightening countenance, he exclaimed:

"Mr. Mitchel, I'm an ass. You are right to laugh at me."

"Nonsense! I defy all other detectives, because Mr. Barnes works with me."

"Bosh!" said the detective, deprecatingly, but pleased nevertheless by the words of flattery. "Well, then, suppose I tell you my story from the beginning?"

"From the beginning, by all means."

"In speaking of the woman whom I set to spy upon Mrs. Gray, you just now mentioned that I had once played the same trick upon your wife. Very true, and not only is this the same trick, but it is the same girl."

"What! Lucette?"

"The same. This is not the first time that she has chosen to resort to her own devices rather than to follow strictly the orders given to her. In this case, however, as I said before, she has done no harm, and on the contrary, I think you would find her report, which I received an hour ago, quite interesting."

"Ah, you have brought it with you?"

"Yes. I will read it to you. Of course it is not addressed to me, neither is there any signature. No names are mentioned except by initial. All this is the girl's own devising, so you see she is not entirely stupid. She writes:

"'At last I have discovered everything.' You observe that she is not unappreciative of her own ability. 'Mr. L. was right. Women are bad conspirators. At least he is right as to Mrs. G. She has dropped the conspiracy entirely, if she ever was a real conspirator, which I doubt, for, though you may not suspect it, she loves her husband. How do I know? Well, a woman has instincts about love. A man may swear eternal devotion to a woman eight hours a day for a year, without convincing her, when she would detect the true lover by the way he ties her shoe-string, unasked. So here. I have not heard madame talking in her sleep, neither has she taken her maid for a confidante, though I think she might find a worse adviser. Still I say she loves her husband. How do I know? When a woman is constantly doing things which add to the comfort of a man, and for which she never receives thanks, because they are such trifles, you may be sure the woman loves the man, and by hundreds of such tokens I know that Mrs. G. is in love with her husband. To reach the next point I must give you an axiom. A woman never loves more than one man at a time. She may have many lovers in the course of a lifetime, but in each instance she imagines that all previous affairs were delusions, and that at last the divine fire consumes her. To this last love she is constant until he proves unworthy, and ofttimes even after. No, a man may be able to love two persons, but a woman's affections are ever centred in a single idol. From which it is a logical deduction that Mrs. G. does not and did not love Mr. L. Then why did she give him the opal? A question which will puzzle you, and for which you are at a loss for an answer.'"

"She is not complimentary," interrupted Mr. Mitchel.

"Not very," said Mr. Barnes, and then he continued reading:

"'This is a question at which I arrived, as you see, by logical mental stages. This is the question to which I have found the reply. This is what I mean when I say I have discovered all: Yesterday afternoon Mr. L. called. Madame hesitated, but finally decided to see him. From her glances in my direction, I was sure she feared I might accidentally find it convenient to be near enough to a keyhole to overhear the conversation which was about to ensue, and, as I did not wish her to make such an "accident" impossible, I innocently suggested that if she intended to receive a visitor, I should be glad to have permission to leave the house for an hour. The trick worked to a charm. Madame seemed only too glad to get rid of me. I hurried downstairs into the back parlor, where, by secreting myself between the heavy portieres and the closed folding-doors, my sharp ears readily followed the conversation, except such few passages as were spoken in very low tones, but which I am sure were unimportant. The details I will give you when I see you. Suffice it to say that I discovered that madame's reason for refusing to let her husband sell the jewel to that crank Mr. M. – '"

"Ah; I see she remembers me," said Mr. Mitchel, with a smile.

"How could she forget your locking her in a room when she was most anxious to be elsewhere? But let me finish this:

"' – to that crank Mr. M. was because Mr. L. was telling her how to make a deal more money out of the jewel. It seems that he has the mate to it, and that the two were stolen from an idol somewhere in Mexico, and that a fabulous sum could be obtained by returning the two gems to the native priests. Just how, I do not know.'"

"So she did not discover everything, after all," said Mr. Mitchel.

"No; but she is right in the main. Her report continues:

"'Madame, however, hesitated to go into the venture, partly because Mr. L. insisted that the matter be kept secret from her husband, and more particularly because the money in exchange was not to be forthcoming immediately. On the yacht she changed her mind impulsively. The result of that you know.'

"That is all," said Mr. Barnes, folding the paper and returning it to his pocket.

"That is all you know?" asked Mr. Mitchel.

"No; that is all that Lucette knows. I know how the fabulous sum of money was to be had in exchange for the two opals."

"Ah; that is more to our immediate purpose. How have you made this discovery?"

"My spies learned practically nothing by shadowing Livingstone, except that he has had several meetings with a half-breed Mexican who calls himself Pedro Domingo. I decided that it would be best for me to interview Señor Domingo myself, rather than to entrust him to a second man."

"What a compliment to our friend Livingstone!" said Mr. Mitchel, with a laugh.

"I found the Mexican suspicious and difficult to approach at first. So I quickly decided that only a bold play would be successful. I told him that I was a detective, and related the incident of the stealing of the opal. At this his eyes glistened, but when I told him that the gem had been sold to a man of enormous wealth who would never again part with it, his eyes glared."

"Yes, Domingo's eyes are glary at times. Go on."

"I explained to him that by this I meant that it would now be impossible for Mr. Livingstone to get the opal, and then I boldly asked him what reward I might expect if I could get it."

"How much did he offer?"

"At first he merely laughed at me, but then I explained that you are my friend, and that you merely buy such things to satisfy a hobby, and that, having no especial desire for this particular jewel, I had little doubt that I could obtain it, provided it would be of great financial advantage to myself. In short, that you would sell to a friend what none other could buy."

"Not bad, Mr. Barnes. What did Domingo say to that?"

"He asked for a day to think it over."

"Which, of course, you granted. What, then, is his final answer?"

"He told me to get the opal first, and then he would talk business."

"Bravo! Domingo is becoming quite a Yankee."

"Of course I watched the man during the interval, in order to learn whether or not he would consult with Mr. L., or any other adviser."

"What did this lead to?"

"It led to Pasquale Sanchez."

"What! More Mexicans?"

"One more only. Sanchez lives in a house near where Domingo has his room. He tells me that he comes from the same district as Domingo. Although Domingo did not make a confidant of him, or even ask his advice, his visit to his friend cleared up some things for me, for by following Domingo I came upon Sanchez."

"What could he know, if, as you say, he was not in the confidence of Domingo?"

"He knew some things which seem to be common knowledge in his native land. He is even more Americanized than his friend, for he fully appreciates a glass of whiskey, though I doubt not the habit was first acquired at home. I should think it would take many years to acquire such a – let me call it – capacity. I never saw a man who could swallow such powerful doses without a change of expression. The only effect seemed to be to loosen his tongue. It is needless to repeat all the stages by which I approached my subject. He knew all about the Aztec opals, – for really there are two of them, – except of course their present whereabouts. I asked him if they would be valuable, supposing that I could get possession of them. He was interested at once. 'You get them, and I show you million dollars.' I explained to him that I might see a million dollars any day by visiting the United States Treasury, upon which, with many imprecations and useless interpolations of bad Spanish, he finally made it clear to me that the priests who have the idol from which the opals were obtained, have practically little power over their tribe while the 'god is in heaven,' as has been explained to the faithful, the priests not caring to exhibit the image without its glowing eyes. These priests, it seems, know where the mine is from which these opals were taken, and they would reveal this secret in exchange for the lost opals, because, though this mine is said to be very rich, they have been unable themselves to find any pieces sufficiently large and brilliant from which to duplicate the lost gems."

"Then you think it was to obtain possession of this opal mine that Mr. Livingstone sought to obtain Mrs. Gray's opal?"

"Undoubtedly. So certain am I of this that I would wager that he will endeavor to get the opal from you."

"Let me read a letter to you, Mr. Barnes."

Mr. Mitchel took out a letter and read as follows:

"'Leroy Mitchel, Esq.: —

"'Dear Sir – In my letter of recent date I offered to you the duplicate of the Aztec Opal which you recently purchased from Mr. Gray. You paid Gray twenty thousand dollars, and I expressed my willingness to sell you mine for five thousand dollars in advance of this sum. In your letter just received, you agree to pay this amount, naming two conditions. First, you ask why I consider my opal worth more than the other, if it is an exact duplicate. Secondly, you wish me to explain what I meant by saying on the yacht that "women are poor conspirators."

"'In reply to your first question, my answer is, that however wealthy I may be I usually do business strictly on business principles. These opals separately are worth in the open market twenty thousand dollars each, which sum you paid to Gray. But considering the history of the gems, and the fact that they are absolute duplicates the one of the other, it is not too much to declare that as soon as one person owns both gems, the value is enhanced twofold. That is to say, that the pair of opals together would be worth seventy or eighty thousand dollars. This being true, I consider it fair to argue that whilst I should not expect more than twenty thousand dollars from any other person in the world, twenty-five thousand is a low sum for me to ask of the man who has the duplicate of this magnificent harlequin opal.

"'In regard to my remark about the "conspirators," the conspiracy in which I had induced Mrs. Gray to take part was entirely honorable, I assure you. I knew of Gray's financial embarrassments and wished to aid him, without, however, permitting him to suspect my hand in the affair. He is so sensitive, you know. I therefore suggested to Mrs. Gray that she entrust her jewel to me, and promised to dispose of the two jewels together, thus realizing the enhanced value. I pointed out that in this manner she would be able to give her husband much more than he could possibly secure by the sale of the one stone.

"'Trusting that I have fully complied with your conditions, I will call upon you at noon to-day, and will bring the opal with me. We can then complete the transaction, unless you change your mind in the interval. Cordially yours, etc.'

"So you see," said Mr. Mitchel, "he offers to sell me his opal, rather than to purchase mine."

"It is strange," said Mr. Barnes, musingly. "Why should he relinquish his hope of getting possession of that mine? I do not believe it. There is some devilish trickery at work. But let me tell you the rest of my story."

"Oh, is there more?"

"Why, certainly. I have not yet explained my reason for thinking you might be in danger."

"Ah, to be sure. My danger. I had forgotten all about it. Pardon my stupidity."

"In further conversation with this Sanchez I put this proposition to him. 'Suppose,' said I, 'that your friend Domingo had one of these opals, and knew the man who had the other. What would he do?' His answer was short, but to the point. 'He get it, even if he kill.'"

"So you think that Domingo might try murder?"

"It is not impossible."

"But, Mr. Barnes, he does not want my life. He wants the opal, and as that is, or rather has been until to-day, in the safety-vaults, how could he get it, even by killing me?"

"You have just admitted that it is not in the vaults at present."

"But it is quite as much out of his reach in my safe here in this room."

"But you might take it out of the safe. You might, in some manner, be persuaded to do so, to show it to some one."

"Very true. In fact, that is why it is here. I must compare my opal with the one which Mr. Livingstone offers for sale, before I part with twenty-five thousand dollars. For you must remember that such a sum is a fabulous price for an opal, even though, as you know, these are the largest in the world."

"From a money standpoint, of course, your precaution is proper. But do you not see that you are really making possible the very danger of which I came to warn you?"

"You mean – "

"Murder in order to get possession of that accursed ill-luck stone. But I fear my warning is not appreciated."

"Indeed, my friend, it is, and I am glad that you have come in person to acquaint me with your anxiety in my behalf. This I will more thoroughly explain to you later. For the present, I may say that I am glad to have you here as a possible witness, in case murder, or any other crime, should be attempted."

"What other crime do you anticipate as possible? Surely not theft?"

"Why not?"

"What! Steal that opal from you, while you are present to see the deed committed? That is a joke." Mr. Barnes laughed heartily.

"Your laugh is a compliment," said Mr. Mitchel. "Yet that is exactly what I most anticipate – theft. I am not sure that it may not be undertaken before my very eyes. Especially as the thief did not hesitate at a table filled with men and women. Sh! He is here."

The electric street-door bell had sounded. Mr. Mitchel arose, and spoke hurriedly in a low tone.

"That is probably Mr. Livingstone come to sell his opal, or to steal mine. We shall see. Especially I desire that you should see. Consequently I have arranged matters in advance. Slip behind this bookcase, which I have placed across the corner that you may have room to breathe. The books on the top shelf have been removed, and the tinted glass of the doors will not obstruct your view. From behind you will be able to see through quite readily."

"Why, you seem to have expected me," said Mr. Barnes, getting into the hiding-place.

"Yes, I expected you," said Mr. Mitchel, vouchsafing no further explanation. "Remember now,

Mr. Barnes, you are not to interfere, whatever happens, unless I call you. All I ask is that you use your eyes, and that good eyes will be required be sure, or I never should have arranged to have an extra pair to aid me on this occasion."

A moment later Williams announced Mr. Livingstone.

"Ask Mr. Livingstone to come up here to the library," said Mr. Mitchel, and a little later he greeted his guest.

"Ah, glad to see you, Mr. Livingstone. Take a seat here by my desk, and we can get right to business. First, though, let me offer you a cigar."

Mr. Livingstone chose one from the box which Mr. Mitchel offered to him, and lighted it as he sat down.

"What a companionable feeling steals over one as he puffs a fine cigar, Mr. Mitchel! Who would accept such an offering as this and betray the confidence of his host?"

"Who, indeed?" said Mr. Mitchel. "But why do you say that?"

"Why, I am not entirely a fool. You do not trust me. You are not sure in your own mind whether or not I committed a theft on board of the yacht."

"Am I not?" Mr. Mitchel asked this in a tone that made Mr. Livingstone look upon it in the light of a question, whereas Mr. Barnes, behind the bookcase, considered it as an answer.

"Why, no," said Mr. Livingstone, replying. "Had you believed that the opal changed hands honorably, even though secretly, under cover of the darkness, you would not have asked me to explain my allusion to 'conspirators.' I trust, however, that my letter made it all clear to you."

"Quite clear."

"Then you are still willing to make the purchase?"

"If you still desire to sell. A certified check for the amount is ready for you. Have you brought the opal?"

"Yes. Have you the duplicate? It would be well to compare them before you purchase."

"If you do not mind, I will do so."

Mr. Mitchel turned to his safe and brought out a box which Mr. Barnes thought he recognized. Opening it he drew out a marvellous string of pearls, which he laid aside, while he took from beneath, a velvet case which contained the opal. Returning the pearls to the box he restored that to the safe, which he locked.

"Now, if you will let me see your opal," said Mr. Mitchel, "I will compare the gems."

"Here it is," said Mr. Livingstone, handing Mr. Mitchel his opal.

Mr. Mitchel took the two opals in his hand, and, as they lay side by side, he examined them closely, observing the play of light as he turned them in various positions. To his critical eye they were marvellously beautiful; matchless, though matched. None could see these two and wonder that the old priests in Mexico had searched in vain for a second pair like them.

"Do you know why these opals are so exactly alike?" asked Mr. Livingstone.

"I am not sure," said Mr. Mitchel, apparently absorbed in his scrutiny of the opals. "I have heard many reasons suggested. If you know the true explanation, suppose you tell me."

"Willingly. You will observe that in each opal red lights seem to predominate on one side, while the blue and green are reflected from the other. Originally, this was one great egg-shaped opal, and it was cut in that shape, and then poised in the forehead of a single-eyed idol by the priests of a thousand years ago. By an ingenious mechanism the eye could be made to revolve in its socket, so that either the red or the blue-green side would be visible, as it suited the purpose of the priests, when overawing the tribesmen by pretended prophecies and other miraculous performances. In more recent times, since the advent of the Christians, one-eyed idols are not so plausible, and the priests cut the opal in half, thus making it serve in what may be termed a modernized idol."

"Yes, I have heard that tale before. In fact, I have a metal ring which I was told would exactly encircle the two opals, if placed together to form an egg."

"How could you have such a thing?" asked Mr. Livingstone, with genuine surprise.

"The man who stole the jewels, so the story goes, wishing to enhance their value as much as possible, arranged this as a scheme by which the genuineness of the opals could be tested. He placed the opals together, as before they were cut, and had a silver band made which would exactly clasp them in that position. This band opens and shuts with a spring catch, like a bracelet, and as, when closed, it exactly fits the opals, holding the two firmly together, the owner of the band could easily tell whether the true opals were before him, or not. In some way the opals were next stolen without the band, and their whereabouts was unknown when a dealer in Naples told me the story of the silver band, which he offered to sell me. I scarcely credited his tale, but as all large jewels might in time be offered to me, I thought it well to purchase the band."