At the foot of the stairs, Mr. Gryce excused himself, and calling in two or three men whom he had left outside, had the valet removed before taking Miss Butterworth back into the study. When all was quiet again, and they found an opportunity to speak, Mr. Gryce remarked:

"One very important thing has been settled by the experiment we have just made. Bartow is acquitted of participation in this crime."

"Then we can give our full attention to the young people. You have heard nothing from them, I suppose?"

"No."

"Nor from the old man who laughed?"

"No."

Miss Butterworth looked disappointed.

"I thought—it seemed very probable—that the scrap of writing you found would inform you who these were. If it was important enough for the dying man to try to swallow it, it certainly should give some clew to his assailant."

"Unfortunately, it does not do so. It was a veritable scrawl, madam, running something like this: 'I return your daughter to you. She is here. Neither she nor you will ever see me again. Remember Evelyn!' And signed, 'Amos's son.'"

"Amos's son! That is Mr. Adams himself."

"So we have every reason to believe."

"Strange! Unaccountable! And the paper inscribed with these words was found clinched between his teeth! Was the handwriting recognized?"

"Yes, as his own, if we can judge from the specimens we have seen of his signature on the fly-leaves of his books."

"Well, mysteries deepen. And the retaining of this paper was so important to him that even in his death throe he thrust it in this strangest of all hiding-places, as being the only one that could be considered safe from search. And the girl! Her first words on coming to herself were: 'You have left that line of writing behind.' Mr. Gryce, those words, few and inexplicable as they are, contain the key to the whole situation. Will you repeat them again, if you please, sentence by sentence?"

"With pleasure, madam; I have said them often enough to myself. First, then: 'I return your daughter to you!'"

"So! Mr. Adams had some one's daughter in charge whom he returns. Whose daughter? Not that young man's daughter, certainly, for that would necessitate her being a small child. Besides, if these words had been meant for his assailant, why make so remarkable an effort to hide them from him?"

"Very true! I have said the same thing to myself."

"Yet, if not for him, for whom, then? For the old gentleman who came in later?"

"It is possible; since hearing of him I have allowed myself to regard this as among the possibilities, especially as the next words of this strange communication are: 'She is here.' Now the only woman who was there a few minutes previous to this old gentleman's visit was the light-haired girl whom you saw carried out."

"Very true; but why do you reason as if this paper had just been written? It might have been an old scrap, referring to past sorrows or secrets."

"These words were written that afternoon. The paper on which they were scrawled was torn from a sheet of letter paper lying on the desk, and the pen with which they were inscribed—you must have noticed where it lay, quite out of its natural place on the extreme edge of the table."

"Certainly, sir; but I had little idea of the significance we might come to attach to it. These words are connected, then, with the girl I saw. And she is not Evelyn or he would not have repeated in this note the bird's catch-word, 'Remember Evelyn!' I wonder if she is Evelyn?" proceeded Miss Butterworth, pointing to the one large picture which adorned the wall.

"We may call her so for the nonce. So melancholy a face may well suggest some painful family secret. But how explain the violent part played by the young man, who is not mentioned in these abrupt and hastily penned sentences! It is all a mystery, madam, a mystery which we are wasting time to attempt to solve."

"Yet I hate to give it up without an effort. Those words, now. There were some other words you have not repeated to me."

"They came before that injunction, 'Remember Evelyn!' They bespoke a resolve. 'Neither she nor you will ever see me again.'"

"Ah! but these few words are very significant, Mr. Gryce. Could he have dealt that blow himself? May he have been a suicide after all?"

"Madam, you have the right to inquire; but from Bartow's pantomime, you must have perceived it is not a self-inflicted blow he mimics, but a maddened thrust from an outraged hand. Let us keep to our first conclusions; only—to be fair to every possibility—the condition of Mr. Adams's affairs and the absence of all family papers and such documents as may usually be found in a wealthy man's desk prove that he had made some preparation for possible death. It may have come sooner than he expected and in another way, but it was a thought he had indulged in, and—madam, I have a confession to make also. I have not been quite fair to my most valued colleague. The study—that most remarkable of rooms—contains a secret which has not been imparted to you; a very peculiar one, madam, which was revealed to me in a rather startling manner. This room can be, or rather could be, cut off entirely from the rest of the house; made a death-trap of, or rather a tomb, in which this incomprehensible man may have intended to die. Look at this plate of steel. It is worked by a mechanism which forces it across this open doorway. I was behind that plate of steel the other night, and these holes had to be made to let me out."

"Ha! You detectives have your experiences! I should not have enjoyed spending that especial evening with you. But what an old-world tragedy we are unearthing here! I declare"—and the good lady actually rubbed her eyes—"I feel as if transported back to mediÆval days. Who says we are living in New York within sound of the cable car and the singing of the telegraph wire?"

"Some men are perfectly capable of bringing the mediÆval into Wall Street. I think Mr. Adams was one of those men. Romanticism tinged all his acts, even the death he died. Nor did it cease with his death. It followed him to the tomb. Witness the cross we found lying on his bosom."

"That was the act of another's hand, the result of another's superstition. That shows the presence of a priest or a woman at the moment he died."

"Yet," proceeded Mr. Gryce, with a somewhat wondering air, "he must have had a grain of hard sense in his make-up. All his contrivances worked. He was a mechanical genius, as well as a lover of mystery."

"An odd combination. Strange that we do not feel his spirit infecting the very air of this study. I could almost wish it did. We might then be led to grasp the key to this mystery."

"That," remarked Mr. Gryce, "can be done in only one way. You have already pointed it out. We must trace the young couple who were present at his death struggle. If they cannot be found the case is hopeless."

"And so," said she, "we come around to the point from which we started—proof positive that we are lost in the woods." And Miss Butterworth rose. She felt that for the time being she, at least, had come to the end of her resources.

Mr. Gryce did not seek to detain her. Indeed, he appeared to be anxious to leave the place himself. They, however, stopped long enough to cast one final look around them. As they did so Miss Butterworth's finger slowly rose.

"See!" said she, "you can hardly perceive from this side of the wall the opening made by the removal of that picture on the stair landing. Wouldn't you say that it was in the midst of those folds of dark-colored tapestry up there?"

"Yes, I had already located that spot as the one. With the picture hung up on the other side, it would be quite invisible."

"One needs to keep one's eyes moving in a case like this. That picture must have been drawn aside several times while we were in this room. Yet we failed to notice it."

"That was from not looking high enough. High and low, Mr. Gryce! What goes on at the level of the eye is apparent to every one."

The smile with which he acknowledged this parting shot and prepared to escort her to the door had less of irony than sadness in it. Was he beginning to realize that years tell even on the most sagacious, and that neither high places nor low would have escaped his attention a dozen years before?