The girl in the green mask leaned against the foot of the bed and idly fingered a revolver which lay in the palm of her daintily gloved hand. The dim glow of the night lamp enveloped her softly, and added a sinister glint to the bright steel of the weapon. Cowering in the bed was another figure — the figure of a woman. Sheets and blankets were drawn up tightly to her chin, and startled eyes peered anxiously, as if fascinated, at the revolver.

“Now please don’t scream!” warned the masked girl. Her voice was quite casual, the tone in which one might have discussed an affair of far removed personal interest. “It would be perfectly useless, and besides dangerous.”

“Who are you?” gasped the woman in the bed, staring horror stricken at the inscrutable mask of her visitor. “What do you want?”

A faint flicker of amusement lay in the shadowy eyes of the masked girl, and her red lips twitched slightly. “I don’t think I can be mistaken,” she said inquiringly. “This is Miss Isabel Leigh Harding?”

“Y-yes,” was the chattering reply.

“Originally of Virginia?”

“Yes.”

“Great-granddaughter of William Tremaine Harding, an officer in the Continental Army about 1775?”

The inflection of the questioning voice had risen almost imperceptibly; but the tone remained coldly, exquisitely courteous. At the last question the masked girl leaned forward a little expectantly.

“Yes,” faltered Miss Harding faintly.

“Good, very good,” commented the masked girl, and there was a note of repressed triumph in her voice. “I congratulate you, Miss Harding, upon your self possession. Under the same circumstances most women would have begun by screaming. I should have myself.”

“But who are you?” demanded Miss Harding again. “How did you get in here? What do you want?”

She sat bolt upright in bed, with less of fear now than curiosity in her manner, and her luxuriant hair tumbled about her semibare shoulders in profuse dishevelment.

At the sudden movement the masked girl took a firmer grip on the revolver, and moved it forward a little threateningly. “Now please don’t make any mistake!” she advised Miss Harding pleasantly. “You will notice that I have drawn the bell rope up beyond your reach and knotted it. The servants are on the floor above in the extreme rear, and I doubt if they would hear a scream. Your companion is away for the night, and besides there is this.” She tapped her weapon significantly. “Furthermore, you may notice that the lamp is beyond your reach; so that you cannot extinguish it as long as you remain in bed.”

Miss Harding saw all these things, and was convinced.

“Now as to your question,” continued the masked girl quietly. “My identity is of absolutely no concern or importance to you. You would not even recognize my name if I gave it to you. How did I get here? By opening an unfastened window in the drawing room on the first floor and walking in. I shall leave it unlatched when I go; so perhaps you had better have some one fasten it, otherwise thieves may enter.” She smiled a little at the astonishment in Miss Harding’s face. “Now as to why I am here and what I want.”

She sat down on the foot of the bed, drew her cloak more closely about her, and folded her hands in her lap. Miss Harding placed a pillow and lounged against it comfortably, watching her visitor in astonishment. Except for the mask and the revolver, it might have been a cozy chat in any woman’s boudoir.

“I came here to borrow from you — borrow, understand,” the masked girl went on, “the least valuable article in your jewel box.”

“My jewel box!” gasped Miss Harding suddenly. She had just thought of it, and glanced around at the table where it lay open.

“Don’t alarm yourself,” the masked girl remarked reassuringly; “I have removed nothing from it.”

The light of the lamp fell full upon the open casket whence radiated multicolored flashes of gems. Miss Harding craned her neck a little to see, and seeing sank back against her pillow with a sigh of relief.

“As I said, I came to borrow one thing,” the masked girl continued evenly. “If I cannot borrow it, I shall take it.”

Miss Harding sat for a moment in mute contemplation of her visitor. She was searching her mind for some tangible explanation of this nightmarish thing. After awhile she shook her head, meaning thereby that even conjecture was futile. “What particular article do you want?” she asked finally.

“Specifically by letter, from the prison in which he was executed by order of the British commander, your great-grandfather, William Tremaine Harding, left a gold bracelet, a plain band, to your grandfather,” the masked girl explained; “Your grandfather, at that time a child, received the bracelet, when twenty-one years old, from the persons who held it in trust for him, and on his death, March 25, 1853, left it to your father. Your father died intestate in April, 1898, and the bracelet passed into your mother’s keeping, there being no son. Your mother died within the last year. Therefore, the bracelet is now, or should be, in your possession. You see,” she concluded, “I have taken pains to acquaint myself with your family history.”

“You have,” Miss Harding assented. “And may I ask why you want this bracelet?”

“I should answer that it was no concern of yours.”

“You said borrow it, I believe?”

“Either I will borrow it or take it.”

“Is there any certainty that it will ever be returned? And if so, when?”

“You will have to take my word for that, of course,” replied the masked girl. “I shall return it within a few days.”

Miss Harding glanced at her jewel box. “Have you looked there?” she inquired.

“Yes,” replied the masked girl. “It isn’t there.”

“Not there?” repeated Miss Harding.

“If it had been there I should have taken it and gone away without disturbing you,” the masked girl went on. “Its absence is what caused me to wake you.”

“Not there!” said Miss Harding again wonderingly, and she moved as if to get up.

“Don’t do that, please!” warned the masked girl quickly. “I shall hand you the box if you like.”

She arose and passed the casket to Miss Harding, who spilled out the contents in her lap.

“Why, it is gone!” she exclaimed.

“Yes, from there,” said the other a little grimly. “Now please tell me immediately where it is. It will save trouble.”

“I don’t know,” replied Miss Harding hopelessly.

The masked girl stared at her coldly for a moment, then drew back the hammer of the revolver until it clicked.

Miss Harding stared in sudden terror.

“All this is merely time wasted,” said the masked girl sternly, coldly. “Either the bracelet or this!” Again she tapped the revolver.

“If it is not here, I don’t know where it is,” Miss Harding rushed on desperately. “I placed it here at ten o’clock tonight — here in this box — when I undressed. I don’t know — I can’t imagine —”

The masked girl tapped the revolver again several times with one gloved finger. “The bracelet!” she demanded impatiently.

Fear was in Miss Harding’s eyes now, and she made a helpless, pleading gesture with both white hands. “You wouldn’t kill me — murder me!” she gasped. “I don’t know. I— Here, take the other jewels. I can’t tell you.”

“The other jewels are of absolutely no use to me,” said the girl coldly. “I want only the bracelet.”

“On my honor,” faltered Miss Harding, “I don’t know where it is. I can’t imagine what has happened to it. I— I—” she stopped helplessly.

The masked girl raised the weapon threateningly, and Miss Harding stared in cringing horror.

“Please, please, I don’t know!” she pleaded hysterically.

For a little while the masked girl was thoughtfully silent. One shoe tapped the floor rhythmically; the eyes were contracted. “I believe you,” she said slowly at last. She arose suddenly and drew her coat closely about her. “Good night,” she added as she started toward the door. There she turned back. “It would not be wise for you to give an alarm for at least half an hour. Then you had better have some one latch the window in the drawing room. I shall leave it unfastened. Good night.”

And she was gone.

Hutchinson Hatch, reporter, had just finished relating the story to The Thinking Machine, incident by incident, as it had been reported to Chief of Detectives Mallory, when the eminent scientist’s aged servant, Martha, tapped on the door of the reception room and entered with a card.

“A lady to see you, sir,” she announced.

The scientist extended one slender white hand, took the card, and glanced at it.

“Your story is merely what Miss Harding told the police?” he inquired of the reporter. “You didn’t get it from Miss Harding herself?”

“No, I didn’t see her.”

“Show the lady in, Martha,” directed The Thinking Machine. She turned and went out, and he passed the card to the reporter.

“By George! it’s Miss Harding herself!” Hatch exclaimed. “Now we can get it all straight.”

There was a little pause, and Martha ushered a young woman into the room. She was girlish, slender, daintily yet immaculately attired, with deep brown eyes, firmly molded chin and mouth, and wavy hair. Hatch’s expression of curiosity gave way to one of frank admiration as he regarded her. There was only the most impersonal sort of interest in the watery blue eyes of The Thinking Machine. She stood for a moment with gaze alternating between the distinguished man of science and the reporter.

“I am Mr. Van Dusen,” explained The Thinking Machine. “Allow me, Miss Harding — Mr. Hatch.”

The girl smiled and offered a gloved hand cordially to each of the two men. The Thinking Machine merely touched it respectfully; Hatch shook it warmly. The eyes were veiled demurely for an instant, then the lids were lifted suddenly, and she favored the newspaper man with a gaze that sent the blood to his cheeks.

“Be seated, Miss Harding,” the scientist invited.

“I hardly know just what I came to say, and just how to say it,” she began uncertainly, and smiled a little. “And anyway I had hoped that you were alone; so —”

“You may speak with perfect freedom before Mr. Hatch,” interrupted The Thinking Machine. “Perhaps I shall be able to aid you; but first will you repeat the history of the bracelet as nearly as you can in the words of the masked woman who called upon you so — so unconventionally.”

The girl’s brows were lifted inquiringly, with a sort of start.

“We were discussing the case when your card was brought in,” continued The Thinking Machine tersely. “We shall continue from that point, if you will be so good.”

The young woman recited the history of the bracelet, slowly and carefully.

“And that statement of the case is correct?” queried the scientist.

“Absolutely, so far as I know,” was the reply.

“And as I understand it, you were in the house alone; that is, alone except for the servants?”

“Yes; I live there alone, except for a companion and two servants. The servants were not within the sound of my voice, even if I had screamed, and Miss Talbott, my companion, it happened, was out for the night.”

The Thinking Machine had dropped back into his chair, with squint eyes turned upward, and long white fingers pressed tip to tip. He sat thus silently for a long time. The girl at last broke the silence.

“Naturally I was a little surprised,” she remarked falteringly, “that I should have appeared just in time to interrupt a discussion of the singular happenings in my home last night; but really —”

“This bracelet,” interrupted the little scientist again. “It was of oval form, perhaps, with no stones set in it, or anything of that sort — merely a band that fastened with an invisible hinge. That’s right, I believe?”

“Quite right, yes,” replied the girl readily.

It occurred to Hatch suddenly that he himself did not know — in fact, had not inquired — the shape of the bracelet. He knew only that it was gold, and of no great value. Knowing nothing about what it looked like, he had not described it to The Thinking Machine; therefore he raised his eyes inquiringly now. The drawn face of the scientist was inscrutable.

“As I started to say,” the girl went on, “the bracelet and the events of last night have no direct connection with the purpose of my visit here.”

“Indeed?” commented the scientist.

“No; I came to see if you could assist me in another way. For instance,” and she fumbled in her pocket book, “I happened to know, Professor Van Dusen, of some of the remarkable things you have accomplished, and I should like to ask if you can throw any light on this for me.”

She drew from the pocketbook a crumpled, yellow sheet of paper — a strip perhaps an inch wide, thin as tissue, glazed, and extraordinarily wrinkled. The Thinking Machine squinted at its manifold irregularities for an instant curiously, nodded, sniffed at it, then slowly began to unfold it, smoothing it out carefully as he went. Hatch leaned forward eagerly and stared. He was a little more than astonished at the end to find that the sheet was blank. The Thinking Machine examined both sides of the paper thoughtfully.

“And where did you find the bracelet at last?” he inquired casually.

“I have reason to believe,” the girl rushed on suddenly, regardless of the question, “that this strip of paper has been substituted for one of real value — I may say one of great value — and I don’t know how to proceed, unless —”

“Where did you find the bracelet?” demanded The Thinking Machine again impatiently.

Hatch would have hesitated a long time before he would have said the girl was disconcerted at the question, or that there had been any real change in the expression of her pretty face. And yet —

“After the masked woman had gone,” she went on calmly, “I summoned the servants and we made a search. We found the bracelet at last. I thought I had tossed it into my jewel box when I removed it last night; but it seems I was careless enough to let it fall down behind my dressing table, and it was there all the time the — the masked woman was in my room.”

“And when did you make this discovery?” asked The Thinking Machine.

“Within a few minutes after she went out.”

“In making your search, you were guided, perhaps, by a belief that in the natural course of events the bracelet could not have disappeared from your jewel box unless some one had entered the room before the masked woman entered; and further that if anyone had entered you would have been awakened?”

“Precisely.” There was another pause. “And now please,” she went on, “what does this blank strip of paper mean?”

“You had expected something with writing on it, of course?”

“That’s just what I had expected,” and she laughed nervously. “You may rest assured I was considerably surprised at finding that.”

“I can imagine you were,” remarked the scientist dryly.

The conversation had reached a point where Hatch was hopelessly lost. The young woman and the scientist were talking with mutual understanding of things that seemed to have no connection with anything that had gone before. What was the paper anyway? Where did it come from? What connection did it have with the affairs of the previous night? How did —

“Mr. Hatch, a match, please,” requested The Thinking Machine.

Wonderingly the reporter produced one and handed it over. The imperturbable man of science lighted it and thrust the mysterious paper into the blaze. The girl arose with a sudden, startled cry, and snatched at the paper desperately, extinguishing the match as she did so. The Thinking Machine turned disapproving eyes on her.

“I thought you were going to burn it!” she gasped.

“There is not the slightest danger of that, Miss Harding,” declared The Thinking Machine coldly. He examined the blank sheet again. “This way, please.”

He arose and led the way into his tiny laboratory across the narrow hall, with the girl following. Hatch trailed behind, wondering vaguely what it was all about. A small brazier flashed into flame as The Thinking Machine applied a match, and curious eyes peered over his shoulders as he held the blank strip, now smoothed out, so that the rising heat would strike it.

For a long time three pairs of eyes were fastened on the mysterious paper, all with understanding now, but nothing appeared. Hatch glanced round at the young woman. Her face wore an expression of tense excitement. The red lips were slightly parted in anticipation, the eyes sparkling, and the cheeks flushed deeply. In staring at her the reporter forgot for the instant everything else, until suddenly:

“There! There! Do you see?”

The exclamation burst from her triumphantly, as faint, scrawly lines grew on the strip suspended over the brazier. Totally oblivious of their presence apparently, The Thinking Machine was squinting steadily at the paper, which was slowly crinkling up into wavy lines under the influence of the heat. Gradually the edges were charring, and the odor of scorched paper filled the room. Still the scientist held the paper over the fire. Just as it seemed inevitable that it would burst into flame, he withdrew it and turned to the girl.

“There was no substitution,” he remarked tersely. “It is sympathetic ink.”

“What does it say?” demanded the young woman abruptly. “What does it mean?”

The Thinking Machine spread the scorched strip of paper on the table before them carefully, and for a long time studied it minutely.

“Really, my dear young woman, I don’t know,” he said crabbedly at last. “It may take days to find out what it means.............