Upon which I plunged into my subject.

“Mrs. Fairbrother wore the real diamond, and no imitation, to the ball. Of this I feel sure. The bit of glass or paste displayed to the coroner’s jury was bright enough, but it was not the star of light I saw burning on her breast as she passed me on her way to the alcove.”

“Miss Van Arsdale!”

“The interest which Mr. Durand displayed in it, the marked excitement into which he was thrown by his first view of its size and splendor, confirm in my mind the evidence which he gave on oath (and he is a well-known diamond expert, you know, and must have been very well aware that he would injure rather than help his cause by this admission) that at that time he believed the stone to be real and of immense value. Wearing such a gem, then, she entered the fatal alcove, and, with a smile on her face, prepared to employ her fascinations on whoever chanced to come within their reach. But now something happened. Please let me tell it my own way. A shout from the driveway, or a bit of snow thrown against the window, drew her attention to a man standing below, holding up a note fastened to the end of a whip-handle. I do not know whether or not you have found that man. If you have—” The inspector made no sign. “I judge that you have not, so I may go on with my suppositions. Mrs. Fairbrother took in this note. She may have expected it and for this reason chose the alcove to sit in, or it may have been a surprise to her. Probably we shall never know the whole truth about it; but what we can know and do, if you are still holding to our compact and viewing this crime in the light of Mr. Durand’s explanations, is that it made a change in her and made her anxious to rid herself of the diamond. It has been decided that the hurried scrawl should read, ‘Take warning. He means to be at the ball. Expect trouble if you do not give him the diamond,’ or something to that effect. But why was it passed up to her unfinished? Was the haste too great? I hardly think so. I believe in another explanation, which points with startling directness to the possibility that the person referred to in this broken communication was not Mr. Durand, but one whom I need not name; and that the reason you have failed to find the messenger, of whose appearance you have received definite information, is that you have not looked among the servants of a certain distinguished visitor in town. Oh,” I burst forth with feverish volubility, as I saw the inspector’s lips open in what could not fail to be a sarcastic utterance, “I know what you feel tempted to reply. Why should a servant deliver a warning against his own master? If you will be patient with me you will soon see; but first I wish to make it clear that Mrs. Fairbrother, having received this warning just before Mr. Durand appeared in the alcove,—reckless, scheming woman that she was!—sought to rid herself of the object against which it was directed in the way we have temporarily accepted as true. Relying on her arts, and possibly misconceiving the nature of Mr. Durand’s interest in her, she hands over the diamond hidden in her rolled-up gloves, which he, without suspicion, carries away with him, thus linking himself indissolubly to a great crime of which another was the perpetrator. That other, or so I believe from my very heart of hearts, was the man I saw leaning against the wall at the foot of the alcove a few minutes before I passed into the supper-room.”

I stopped with a gasp, hardly able to meet the stern and forbidding look with which the inspector sought to restrain what he evidently considered the senseless ravings of a child. But I had come there to speak, and I hastily proceeded before the rebuke thus expressed could formulate itself into words.

“I have some excuse for a declaration so monstrous. Perhaps I am the only person who can satisfy you in regard to a certain fact about which you have expressed some curiosity. Inspector, have you ever solved the mystery of the two broken coffee-cups found amongst the debris at Mrs. Fairbrother’s feet? It did not come out in the inquest, I noticed.”

“Not yet,” he cried, “but—you can not tell me anything about them!”

“Possibly not. But I can tell you this: When I reached the supper-room door that evening I looked back and, providentially or otherwise—only the future can determine that—detected Mr. Grey in the act of lifting two cups from a tray left by some waiter on a table standing just outside the reception-room door. I did not see where he carried them; I only saw his face turned toward the alcove; and as there was no other lady there, or anywhere near there, I have dared to think—”

Here the inspector found speech.

“You saw Mr. Grey lift two cups and turn toward the alcove at a moment we all know to have been critical? You should have told me this before. He may be a possible witness.”