Early morning saw Sweetwater peering into the depths of his closet. The hole was hardly visible. This meant that the book he had pushed across it from the other side had not been removed.

Greatly re-assured by the sight, he awaited his opportunity, and as soon as a suitable one presented itself, prepared the hole for inspection by breaking away its edges and begriming it well with plaster and old dirt. This done, he left matters to arrange themselves; which they did, after this manner.

Mr. Brotherson suddenly developed a great need of him, and it became a common thing for him to spend the half and, sometimes, the whole of the evening in the neighbouring room. This was just what he had worked for, and his constant intercourse with the man whose secret he sought to surprise should have borne fruit. But it did not. Nothing in the eager but painstaking inventor showed a distracted mind or a heavily-burdened soul. Indeed, he was so calm in all his ways, so precise and so self-contained, that Sweetwater often wondered what had become of the fiery agitator and eloquent propagandist of new and startling doctrines.

Then, he thought he understood the riddle. The model was reaching its completion, and Brotherson’s extreme interest in it and the confidence he had in its success swallowed up all lesser emotions. Were the invention to prove a failure—but there was small hope of this. The man was of too well-poised a mind to over-estimate his work or miscalculate its place among modern improvements. Soon he would reach the goal of his desires, be praised, feted, made much of by the very people he now professedly scorned. There was no thoroughfare for Sweetwater here. Another road must be found; some secret, strange and unforeseen method of reaching a soul inaccessible to all ordinary or even extraordinary impressions.

Would a night of thought reveal such a method? Night! the very word brought inspiration. A man is not his full self at night. Secrets which, under the ordinary circumstances of everyday life, lie too deep for surprise, creep from their hiding-places in the dismal hours of universal quiet, and lips which are dumb to the most subtle of questioners break into strange and self-revealing mutterings when sleep lies heavy on ear and eye and the forces of life and death are released to play with the rudderless spirit.

It was in different words from these that Sweetwater reasoned, no doubt, but his conclusions were the same, and as he continued to brood over them, he saw a chance—a fool’s chance, possibly, (but fools sometimes win where wise men fail) of reaching those depths he still believed in, notwithstanding his failure to sound them.

Addressing a letter to his friend in Twenty-ninth Street, he awaited reply in the shape of a small package he had ordered sent to the corner drug-store. When it came, he carried it home in a state of mingled hope and misgiving. Was he about to cap his fortnight of disappointment by another signal failure; end the matter by disclosing his hand; lose all, or win all by an experiment as daring and possibly as fanciful as were his continued suspicions of this seemingly upright and undoubtedly busy man?

He made no attempt to argue the question. The event called for the exercise of the most dogged elements in his character and upon these he must rely. He would make the effort he contemplated, simply because he was minded to do so. That was all there was to it. But any one noting him well that night, would have seen that he ate little and consulted his watch continually. Sweetwater had not yet passed the line where work becomes routine and the feelings remain totally under control.

Brotherson was unusually active and alert that evening. He was anxious to fit one delicate bit of mechanism into another, and he was continually interrupted by visitors. Some big event was on in the socialistic world, and his presence was eagerly demanded by one brotherhood after another. Sweetwater, posted at his loop-hole, heard the arguments advanced by each separate spokesman, followed by Brotherson’s unvarying reply: that when his work was done and he had proved his right to approach them with a message, they might look to hear from him again; but not before. His patience was inexhaustible, but he showed himself relieved when the hour grew too late for further interruption. He began to whistle—a token that all was going well with him, and Sweetwater, who had come to understand some of his moods, looked forward to an hour or two of continuous work on Brotherson’s part and of dreary and impatient waiting on his own. But, as so many times before, he misread the man. Earlier than common—much earlier, in fact, Mr. Brotherson laid down his tools and gave himself up to a restless pacing of the floor. This was not usual with him. Nor did he often indulge himself in playing on the piano as he did to-night, beginning with a few heavenly strains and ending with a bang that made the key-board jump. Certainly something was amiss in the quarter where peace had hitherto reigned undisturbed. Had the depths begun to heave, or were physical causes alone responsible for these unwonted ebullitions of feeling?

The question was immaterial. Either would form an excellent preparation for the coup planned by Sweetwater; and when, after another hour of uncertainty, perfect silence greeted him from his neighbour’s room, hope had soared again on exultant wing, far above all former discouragements.

Mr. Brotherson’s bed was in a remote corner from the loop-hole made by Sweetwater; but in the stillness now pervading the whole building, the latter could hear his even breathing very distinctly. He was in a deep sleep.

The young detective’s moment had come.

Taking from his breast a small box, he placed it on a shelf close against the partition. An instant of quiet listening, then he touched a spring in the side of the box and laid his ear, in haste, to his loop-hole.

A strain of well-known music broke softly, from the box and sent its vibrations through the wall.

It was answered instantly by a stir within; then, as the noble air continued, awakening memories of that fatal instant when it crashed through the corridors of the Hotel Clermont, drowning Miss Challoner’s cry if not the sound of her fall, a word burst from the sleeping man’s lips which carried its own message to the listening detective.

It was Edith! Miss Challoner’s first name, and the tone bespoke a shaken soul.

Sweetwater, gasping with excitement, caught the box from the shelf and silenced it. It had done its work and it was no part of Sweetwater’s plan to have this strain located, or even to be thought real. But its echo still lingered in Brotherson’s otherwise unconscious ears; for another “Edith!” escaped his lips, followed by a smothered but forceful utterance of these five words, “You know I promised you—”

Promised her what? He did not say. Would he have done so had the music lasted a trifle longer? Would he yet complete his sentence? Sweetwater trembled with eagerness and listened breathlessly for the next sound. Brotherson was awake. He was tossing in his bed. Now he has leaped to the floor. Sweetwater hears him groan, then comes another silence, broken at last by the sound of his body falling back upon the bed and the troubled ejaculation of “Good God!” wrung from lips no torture could have forced into complaint under any daytime conditions.

Sweetwater continued to listen, but he had heard all, and after some few minutes longer of fruitless waiting, he withdrew from his post. The episode was over. He would hear no more that night.

Was he satisfied? Certainly the event, puerile as it might seem to some, had opened up strange vistas to his aroused imagination. The words “Edith, you know I promised you—” were in themselves provocative of strange and doubtful conjectures. Had the sleeper under the influence of a strain of music indissolubly associated with the death of Miss Challoner, been so completely forced back into the circumstances and environment of that moment that his mind had taken up and his lips repeated the thoughts with which that moment of horror was charged? Sweetwater imagined the scene—saw the figure of Brotherson hesitating at the top of the stairs—saw hers advancing from the writing-room, with startled and uplifted hand—heard the music—the crash of that great finale—and decided, without hesitation, that the words he had just heard were indeed the thoughts of that moment. “Edith, you know I promised you—” What had he promised? What she received was death! Had this been in his mind? Would this have been the termination of the sentence had he wakened less soon to consciousness and caution?

Sweetwater dared to believe it. He was no nearer comprehending the mystery it involved than he had been before, but he felt sure that he had been given one true and positive glimpse into this harassed soul which showed its deeply hidden secret to be both deadly and fearsome; and happy to have won his way so far into the mystic labyrinth he had sworn to pierce, he rested in happy unconsciousness till morning when—

Could it be? Was it he who was dreaming now, or was the event of the night a mere farce of his own imagining? Mr. Brotherson was whistling in his room, gaily and with ever increasing verve, and the tune which filled the whole floor with music was the same grand finale from William Tell which had seemed to work such magic in the night. As Sweetwater caught the mellow but indifferent notes sounding from those lips of brass, he dragged forth the music-box he held hidden in his coat pocket, and flinging it on the floor stamped upon it.

“The man is too strong for me,” he cried. “His heart is granite; he meets my every move. What am I to do now?”