'What guests were on the yacht?'
  'I will tell you everything in order, as the facts were presented to me. Mr Gray enumerated the party as follows. Besides himself and his wife, there were his wife's sister, Mrs Eugene Cortlandt, and her husband, a Wall Street broker. Also, Mr Arthur Livingstone, and his sister, and a Mr Dermett Moore, a young man supposed to be devoting himself to Miss Livingstone.'
  'That makes seven persons, three of whom are women. I ought to say, Mr Barnes, that, though Mr Gray is a club friend, I am not personally acquainted with his wife, nor with the others. So I have no advantage over you.'
  'I will come at once to the curious incident which made my presence desirable. According to Mr Gray's story, the dinner had proceeded as far as the roast, when suddenly there was a slight shock as the yacht touched, and at the same time the lamps spluttered and then went out, leaving the room totally dark. A second later the vessel righted herself and sped on, so that before any panic ensued, it was evident to all that the danger had passed. The gentlemen begged the ladies to resume their seats, and remain quiet until the lamps were lighted; this, however, the attendants were unable to do, and they were ordered to bring fresh lamps. Thus there was almost total darkness for several minutes.'
  'During which, I presume, the person who planned the affair readily consummated his design?'
  'So you think that the whole series of events was pre-arranged? Be that as it may, something did happen in that dark room. The women had started from their seats when the yacht touched, and when they groped their way back in the darkness some of them found the wrong places, as was seen when the fresh lamps were brought. This was considered a good joke, and there was some laughter, which was suddenly checked by an exclamation from Mr Gray, who quickly asked his wife, "Where is your opal?"'
  'Her opal?' asked Mr Mitchel, in tones which showed that his greatest interest was now aroused. 'Do you mean, Mr Barnes, that she was wearing the Azteck opal?'
  'Oh! You know the gem?'
  'I know nearly all gems of great value; but what of this one?'
  'Mrs Gray and her sister, Mrs Cortlandt, had both donned décolleté costumes for this occasion, and Mrs Gray had worn this opal as a pendant to a thin gold chain which hung round her neck. At Mr Gray's question, all looked towards his wife, and it was noted that the clasp was open, and the opal missing. Of course it was supposed that it had merely fallen to the floor, and a search was immediately instituted. But the opal could not be found.'
  'That is certainly a very significant fact,' said Mr Mitchel. 'But was the search thorough?'
  'I should say extremely thorough, when we consider it was not conducted by a detective, who is supposed to be an expert in such matters. Mr Gray described to me what was done, and he seems to have taken every precaution. He sent the attendants out of the salon, and he and his guests systematically examined every part of the room.'
  'Except the place where the opal really was concealed, you mean.'
  'With that exception, of course, since they did not find the jewel. Not satisfied with this search by lamplight, Mr Gray locked the salon, so that no one could enter it during the night, and another investigation was made in the morning.'
  'The pockets of the seven persons present were not examined, I presume?'
  'No! I asked Mr Gray why this had been omitted, and he said that it was an indignity which he could not possibly show to a guest. As you have asked this question, Mr Mitchel, it is only fair for me to tell you that when I spoke to Mr Gray on the subject he seemed very much confused. Nevertheless, however unwilling he may have been to search those of his guests who are innocent, he emphatically told me that if I had reasonable proof that any one present had purloined the opal, he wished that individual to be treated as any other thief, without regard to sex or social position.'
  'One can scarcely blame him, because that opal was worth a fabulous sum. I have myself offered Gray twenty-five thousand dollars for it, which was refused. This opal is one of the eyes of an Azteck Idol, and if the other could be found, the two would be as interesting as any jewels in the world.'
  'That is the story which I was asked to unravel,' continued Mr Barnes, 'and I must now relate to you what steps I have taken towards that end. It appears that, because of the loss of the jewels, no person has left the yacht, although no restraint was placed upon any one by Mr Gray. All knew, however, that he had sent for a detective, and it was natural that no one should offer to go until formally dismissed by the host. My plan, then, was to have a private interview with each of the seven persons who had been present at the dinner.'
  'Then you exempted the attendants from your suspicions?'
  'I did. There was but one way by which one of the servants could have stolen the opal, and this was prevented by Mr Gray. It was possible that the opal had fallen on the floor, and, though not found at night, a servant might have discovered and have appropriated it on the following morning, had he been able to enter the salon. But Mr Gray had locked the doors. No servant, however bold, would have been able to take the opal from the lady's neck.'
  'I think your reasoning is good, and we will confine ourselves to the original seven.'
  'After my interview with Mr Gray, I asked to have Mrs Gray sent in to me. She came in, and at once I noted that she placed herself on the defensive. Women frequently adopt that manner with a detective. Her story was very brief. The main point was that she was aware of the theft before the lamps were relighted. In fact, she felt some one's arms steal around her neck, and knew when the opal was taken. I asked why she had made no outcry, and whether she suspected any special person. To these questions she replied that she supposed it was merely a joke perpetrated in the darkness, and therefore had made no resistance. She would not name any one as suspected by her, but she was willing to tell me that the arms were bare, as she detected when they touched her neck. I must say here, that although Miss Livingstone's dress was not cut low in the neck, it was, practically, sleeveless; and Mrs Cortlandt's dress had no sleeves at all. One other significant statement made by this lady was that her husband had mentioned to her your offer of twenty-five thousand dollars for the opal, and had urged her to permit him to sell it, but she had refused.'
  'So! It was Madam that would not sell. The plot thickens!'
  'You will observe, of course, the point about the naked arms of the thief. I therefore sent for Mrs Cortlandt next. She had a curious story to tell. Unlike her sister, she was quite willing to express her suspicions. Indeed, she plainly intimated that she supposed that Mr Gray himself had taken the jewel. I will endeavour to repeat her words:
  '"Mr Barnes," said she, "the affair is very simple. Gray is a miserable old skinflint. A Mr Mitchel, a crank who collects gems, offered to buy that opal, and he has been bothering my sister for it ever since. When the lamps went out, he took the opportunity to steal it. I do not think this, I know it. How? Well, on account of the confusion and darkness, I sat in my sister's seat when I returned to the table. This explains his mistake, but he put his arms round my neck, and deliberately felt for the opal. I did not understand his purpose at the time, but now it is very evident."
  '"Yes, madam," said I, "but how do you know it was Mr Gray?"
  '"Why, I grabbed his hand, and before he could pull it away I felt the large cameo ring on his little finger. Oh! there is no doubt whatever."
  'I asked her whether Mr Gray had his sleeves rolled up, and though she could not understand the purport of the question, she said "No". Next I had Miss Livingstone come in. She is a slight, tremulous young lady, who cries at the slightest provocation. During the interview, brief as it was, it was only by the greatest diplomacy that I avoided a scene of hysterics. She tried very hard to convince me that she knew absolutely nothing. She had not left her seat during the disturbance; of that she was sure. So how could she know anything about it? I asked her to name the one whom she thought might have taken the opal, and at this her agitation reached such a climax that I was obliged to let her go.'
  'You gained very little from her I should say.'
  'In a case of this kind, Mr Mitchel, where the criminal is surely one of a very few persons, we cannot fail to gain something from each person's story. A significant feature here was that though Miss Livingstone assures us that she did not leave her seat, she was sitting in a different place when the lamps were lighted again.'
  'That might mean anything or nothing.'
  'Exactly! but we are not deducing values yet. Mr Dermett Moore came to me next, and he is a straightforward, honest man if I ever saw one. He declared that the whole affair was a great mystery to him, and that, while ordinarily he would not care anything about it, he could not but be somewhat interested because he thought that one of the ladies, he would not say which one, suspected him. Mr Livingstone also impressed me favourably in spite of the fact that he did not remove his cigarette from his mouth throughout the whole of my interview with him. He declined to name the person suspected by him, though he admitted that he could do so. He made this significant remark:
  '"You are a detective of experience, Mr Barnes, and ought to be able to decide which man amongst us could place his arms around Mrs Gray's neck without causing her to cry out. But if your imagination fails you, suppose you enquire into the financial standing of all of us, and see which one would be most likely to profit by thieving? Ask Mr Cortlandt."'
  'Evidently Mr Livingstone knows more than he tells.'
  'Yet he told enough for one to guess his suspicions, and to understand the delicacy which prompted him to say no more. He, however, gave me a good point upon which to question Mr Cortlandt. When I asked that gentleman if any of the men happened to be in pecuniary difficulties, he became grave at once. I will give you his answer.
  '"Mr Livingstone and Mr Moore are both exceedingly wealthy men, and I am a millionaire, in very satisfactory business circumstances at present. But I am very sorry to say, that though our host, Mr Gray, is also a distinctly rich man, he has met with some reverses recently, and I can conceive that ready money would be useful to him. But for all that, it is preposterous to believe what your question evidently indicates. None of the persons in this party is a thief, and least of all could we suspect Mr Gray. I am sure that if he wished his wife's opal, she would give it to him cheerily. No, Mr Barnes, the opal is in some crack, or crevice, which we have overlooked. It is lost, not stolen."
  'That ended the interviews with the several persons present, but I made one or two other enquiries, from which I elicited at least two significant facts. First, it was Mr Gray himself who had indicated the course by which the yacht was steered last night, and which ran her over a sand-bar. Second, someone had nearly emptied the oil from the lamps, so that they would have burned out in a short time, even though the yacht had not touched.'
  'These, then, are your facts? And from these you have solved the problem? Well, Mr Barnes, who stole the opal?'
  'Mr Mitchel, I have told you all I know, but I wish you to work out a solution before I reveal my own opinion.'
  'I have already done so, Mr Barnes. Here! I will write my suspicion on a bit of paper. So! Now tell me yours, and you shall know mine afterwards.'
  'Why, to my mind it is very simple. Mr Gray, failing to obtain the opal from his wife by fair means, resorted to a trick. He removed the oil from the lamps, and charted out a course for his yacht which would take her over a sand-bar, and when the opportune moment came he stole the jewel. His actions since then have been merely to cover his crime, by shrouding the affair with mystery. By insisting upon a thorough search, and even sending for a detective, he makes it impossible for those who were present to accuse him hereafter. Undoubtedly Mr Cortlandt's opinion will be the one generally adopted. Now what do you think?'
  'I think I will go with you at once, and board the yacht
Idler
.'
  'But you have not told me whom you suspect,' said Mr Barnes, somewhat irritated.
  'Oh! That's immaterial,' said Mr Mitchel, calmly preparing for the street. 'I do not suspect Mr Gray, so if you are correct you will have shown better ability than I. Come! Let us hurry!'
  On their way to the dock, from which they were to take the little steam launch which was waiting to carry the detective back to the yacht, Mr Barnes asked Mr Mitchel the following questions:
  'Mr Mitchel,' said he, 'you will note that Mrs Cortlandt alluded to you as a "crank who collects gems". I must admit that I have myself harboured a great curiosity as to your reasons for purchasing jewels, which are valued beyond a mere conservative commercial price. Would you mind explaining why you began your collection?'
  'I seldom explain my motives to others, especially when they relate to my more important pursuits in life. But in view of all that has passed between us, I think your curiosity justifiable, and I will gratify it. To begin with, I am a very wealthy man. I inherited great riches, and I have made a fortune myself. Have you any conception of the difficulties which harass a man of means?'
  'Perhaps not in minute detail, though I can guess that the lot of the rich is not as free from care as the pauper thinks it is.'
  'The point is this: the difficulty with a poor man is to get rich, while with the rich man the greatest trouble is to prevent the increase of his wealth. Some men, of course, make no effort in that direction, and those men are a menace to society. My own idea of the proper use of a fortune is to manage it for the benefit of others, as well as one's self, and especially to prevent its increase.'