IT WAS the belief of Saxe and his friends that the person guilty of the outrage against them was none other than Hartley Masters. Now, at last, Roy confided to his associates the adventure in the night, when he had discovered the presence of the safe hidden within the wall. The others flouted him as he had anticipated over his failure to capture the intruder and his subsequent inability to learn the secret of the spring in the wainscoting. They accepted without hesitation his assurance that the night prowler had been Masters, and their wrath flamed hot against the engineer, who in his later effort had not scrupled to attempt the murder of five men. They determined to take active measures against the fellow for the sake of their own safety. Roy volunteered to wage a campaign against the enemy, to seek out his whereabouts, to trail him, to get evidence against him, and finally to make him prisoner. The others, meantime, would continue their quest for further clues to the treasure. First of all, they busied themselves with hunting for the concealed safe, after its exact situation had been indicated by Roy, and three days passed in fruitless experimenting on the intricacies of the carved wainscoting.

Roy visited the hamlet at the foot of the lake, where was situated the hotel in which the engineer had been a guest. He learned, to his disappointment, that Masters had taken his departure a week before. He assured himself that this departure had been a real one by inquiries at the station. Further questioning of residents elicited the information that the engineer had thereafter been seen by none. Nevertheless, Roy was far from being convinced by this information that the engineer had actually taken himself off. He was, on the contrary, almost, if not quite, certain that Masters had merely made use of the train for an ostensible departure, in order to avoid the possibility of his presence in the neighborhood appearing as evidence against him in the event of any suspicion that might arise. Afterward, as Roy imagined, he had returned to some out-of-the-way place in the forest, where he could eat and sleep unmolested, and thence spy out the land for the execution of his villainous projects. Doubtless in his employment as an engineer, he had often lived roughly, and the season of the year would make life in the open no hardship. Roy, therefore, set himself to a search of the countryside, hoping somewhere to chance on a trace of the enemy’s camp. In this, he was unsuccessful. After two days of weary tramping, it occurred to him that he could serve his purpose equally well by strolling in pleasant paths with May Thurston at his side.

This improved method was adopted. Roy told the girl nothing as to his desire of finding Masters, but he told her other things a-plenty; and the two of them grew daily more content.

It was Margaret West who finally hit on the spring that moved the wainscoting, for Saxe had let her know the story told by Roy, and she had amused herself by seeking to master the mystery. Actually, beyond her satisfaction in having succeeded where the others had failed, nothing was accomplished, since the vault was empty, and no hint as to the disposal of the gold could be gleaned from its bareness. Yet, new knowledge of the secret was soon to come.

Billy Walker’s pride of intellect had been aroused to the utmost by the difficulty of the task that confronted him. Hour after hour, day after day, he pored over the manuscript, of which the cryptic significance ever escaped all efforts of his ingenuity. It seemed to him that he had, in fact, scrutinized every possible aspect in which the writing might be viewed, and still the veil lay impenetrable over the mystery. He would have been in despair, had he been of a humbler mind, but his intellectual egotism would not suffer him to confess defeat, even to himself. So, he persisted in the struggle to solve this baffling problem—did indeed but strive the harder as the days passed. The others admitted that the difficulties were too great for their overcoming. Billy replied to their lamentations with braggart boasting that he would yet conquer. Nevertheless, at the last, he owed the hint he needed to Saxe.The four men were lounging on the porch of a morning. The languor of summer had grown within a few days, and the four were taking their ease. Billy Walker was crouched in the deeps of a huge chair; David sprawled on a heap of cushions; Roy stretched lazily in a hammock, reminiscent of long siestas in the southland. Saxe alone showed any evidence of alertness. He sat erect at the head of the steps, with the manuscript of the gold song lying on his knees. Ostensibly, his attention was fixed on the music. From time to time, he jabbed the score impatiently with a pencil point. But often, he shot glances of longing toward the stairway, by which, sooner or later, Margaret West must descend. Silence had fallen on the group. A sense of discouragement was in the air. The only sounds were the gossiping of the English sparrows about the eaves, the faint rustling of leaves when the breeze stirred them, the distressful grunt that accompanied any change of position by Billy Walker, the whish of a match as someone lighted a fresh cigarette.

The real activity was on the part of Billy, whose mind, while his body lolled, was nimbly busy over the miser’s manuscript, which his imagination held visible before him. Then, presently, he craved the stimulus of a sight of the actual. He hoisted his cumbersome bulk out of the chair, and went stiffly across the veranda to where Saxe sat with the music. There, he stood for a minute looking down at the notes. His beetling brows were lowering, a low rumble of displeasure came from his heavy lips, he thrust a hand vehemently through the rough shock of hair, his small eyes, with the whites tainted by jaundice, fairly glared down at the elusive script wherein lay knowledge of Abernethey’s gold.

Of a sudden, wonder grew on his face. Doubt, fear, hope, joy, followed. He bent awkwardly, but swiftly, snatched the paper, and immediately stalked off into the cottage and up the stairs to his bedroom, without a word of explanation or apology. Saxe shrugged his shoulders, and smiled whimsically. The others paid no attention whatsoever.

It was a half-hour later when Billy returned to the porch. His manner was wholly changed. He was radiant with a supreme triumph of pride. The others did not look up, as he again seated himself in the easy chair. But the man was so surcharged with exultation that his mood sent its challenges vibrant to their souls. Presently, one turned to stare at him, and then another, and then the third. He met their gaze with eyes that were aglow, and a smile of delight bent the coarse lips. He nodded slowly, as in answer to their mute questioning, and spoke:

“Well, my dilatory friends,” he began genially, “your confidence in me, which has enabled you to retain your calm while yourselves accomplishing nothing, was not misplaced. After a considerable period of unremitting toil over the manuscript left for our guidance by the ingenious deceased—by the way, Saxe, that song of gold, as you call it, is perfectly good music, isn’t it?”

The three were gazing on Billy Walker with wide eyes. Their astonishment was so great that, for the moment, they did not question the leisurely manner of the sage’s introduction. Instead, Saxe answered the seemingly irrelevant interrogation obediently.

“It’s perfectly good music—in the sense you mean—yes.”

“Then,” Billy declared, “I take off my hat to the late Mr. Abernethey. The reason for this burst of enthusiasm on my part lies in the fact that out of a perfectly good piece of music, he has made, also, a perfectly good chart—for our guidance to the treasure. As to the chart, I myself speak as an authority, since I have found it.” Billy regarded his friends with an expression of intense self-satisfaction.

Roy was sitting up in the hammock now, with his jaw thrust forward a little, and his eyes hard in the excitement of the minute. David was goggling, with his mouth open in amazement over the unexpected announcement. Saxe betrayed his emotion by the tenseness of his features, the rigidity of his pose, the sparkle in his keen, gray eyes.

It was evident that the successful investigator was hugely enjoying the sensation he had created. He delighted in the importance of his accomplishment, gloried in the stunning effect of it on his companions. He smiled broadly, chuckled in a rumbling fashion of his own, and finally lighted one of his black cigars with irritating slowness. He rather hoped that someone might exclaim with impatience against this wanton delay, but none did. They endured the suspense in apparent calm, moveless, expectant. So at last, Billy deigned to proceed with the account of his achievement in solving the mystery contrived by the miser.

“I owe the final suggestion by which I won out to Saxe,” he declared frankly, with an appreciative nod in his friend’s direction. “He, however, really deserves no credit, since what he did was merely by chance, without any intention, and would never have amounted to anything, if it hadn’t been for the fact that I happened to see what he had done, and to take advantage of it in an orderly and logical way. Only, I wish it understood that he served as the unconscious instrument of destiny in the matter, and as such unconscious instrument he should be recognized. Probably, I should have arrived at the fact in time without his aid, but to it I owe success on this present occasion.”

“What in the world did I do?” Saxe demanded, in amazement.

“I’ll explain in a minute,” Billy replied. “I have in mind first to exhibit this to you.” He held up a sheet of paper, which he had drawn from his pocket. It was of about the size of that on which Abernethey’s composition had been written. It showed two irregular lines running across it, drawn by pencil. “Glance at this, if you please,” he directed.

The others did so; but their bewildered expression showed that they were still unenlightened as to the bearing of the scant diagram on the revelation concerning the hidden gold. Billy chuckled again in contemplation of their failure to comprehend. Then, he brought forth a second sheet, and held it, also, for their inspection. In this instance, the paper was turned with its greater length horizontal, and the two lines of the other sheet had been joined, so that the one irregular tracing extended over the full page.

David slapped his thigh with violence.“By the Lord Harry, it’s a map!” he cried, in glee. “A regular map, Billy, my boy!” His eyes bulged forth until they threatened to jump from their sockets.

Roy’s jaw shot out a bit farther.

“Yes, it’s a map,” he agreed; and his voice was strangely gentle, as it usually was in his moments of greatest excitement. “It’s a map. Bully for Billy!” His face lighted with a charming smile, and his eyes grew soft as he turned them to the rough-hewn face of the discoverer, who appeared highly gratified.

Saxe took the sheet of paper out of his friend’s hand, and studied it with eager eyes. For the first time in days, hope leaped in his breast.

“Yes, it’s a map,” he declared, echoing the others. “But I don’t understand. Tell us, Billy.”

Billy actually preened himself, in an ungainly manner peculiarly his own, and assumed a most pedantic air, as he went forward with the explanation:

“Saxe was sitting here, with his eyes fixed on the old man’s manuscript, but with his mind elsewhere. I was here in my chair, with all the power of my brain concentrated on that same manuscript, trying to get some suggestion for working out the tangle. Was it merely restlessness under repeated failure, or was it an instinct that moved me, or just chance? Anyhow, I got up, and crossed over to Saxe, and stood looking down at the music, although I had every line of it clear in memory—as clear as the written page itself. But, this time, in spite of the perfect recollection I had of it, I saw something new. That’s how the thing started. It was Saxe’s doing.”

“Oh, do get on with the explanation,” Temple urged. “What was it I did? I haven’t the shadow of an idea.”

“It’s simple enough,” Billy said. “Just absent-mindedly, you sat there with a pencil in your hand, and made ticks over certain notes. As I looked down at the sheet, my attention was especially caught by these, for the excellent reason that they had not been there before. Without any volition on my part, I stood there considering the pencil marks. Within a half-minute, the great idea hit me. In the first rush, I was sure it was the right one; but I wanted to be alone to work it out. So, I just swooped down on the manuscript, and carried it off to my room. Now, to present the case in orderly sequence, here is what we may term Exhibit A.”

Billy took from his pocket a third sheet, which he gave to Saxe. This proved to be the original manuscript of the music, with the pencil markings made by Saxe. The heir of Abernethey examined the page closely, but his expression of bewilderment did not pass. Roy and David left their places to look over the other’s shoulder. For nearly a minute, the three held their gaze curiously on the sheet. Then, of one accord, they looked up, to meet the amused glance of Billy Walker.

“Well?” they demanded, in a single voice.

“You have observed the pencil marks?” came the question; and the three nodded assent.

This is the manner in which the manuscript had been affected by the absent-minded action of Saxe: