“I told ’em so. I told ’em something would happen. I warned those boys they’d get into trouble if they didn’t quit gettin’ so gay. Hal isn’t a gay one, but he can easy be a victim of a trick of one o’ those careless, dare-devil kids.”

Mr. Frankland and Mr. Porter both heard Pepper mutter thus to himself as they followed the doctor toward the waterfall whence the scream of a human voice seemed to come, but they paid little attention to his words, for they knew his peculiarities and attached little importance to his grumbling. Nevertheless, Pepper believed all he said, and more. Only a few days earlier he had observed some of the boys engaged in tying the long grass across the path that led from the stables to the west timberland on Lakefarm. Then he lectured them, promising that they would come to no happy end.

“You boys will be the death of somebody one o’ these fine days, and then you’ll begin to do some thinkin’,” he declared, as he strode along, breaking with a strong kick each of the “trips” that the mischievous youngsters had prepared. “And you, Frank Bowler, are well nicknamed ‘Bad.’ If you don’t end on the gallows, I’m dreamin’.”

Frank seemed to be the leader in this escapade. He would have liked to have made a smart reply to this direful prophecy, but for once in his life he thought twice.

This was only one of many occasions of which the old Englishman took advantage to hand out his advice. He was really a good-hearted and well-intending fellow, and no doubt did some of the boys considerable good. But there were a few of the latter who couldn’t “go the old geezer,” and Frank Bowler was one of them.

Why it was, he could never tell; but Mr. Humphrey had a “feeling in his bones” that one of the mischief makers of the school was connected with the disappearance of Hal Kenyon. And this was what he meant when he muttered the words overheard by Mr. Frankland and Mr. Porter. Although he was the one who called particular attention to the strange sound that seemed to issue from the waterfall, he did not regard it as seriously as did the others. He was thinking more of certain boys back at the school than of the mystery close at hand. True, his wonder was aroused at the sound issuing from the cataract, but his reason would not permit him to connect that with the disappearance of Hal. He was wishing that he were now back at Lakefarm closeted with “some of those bad boys and sweating the truth out o’ them.”

“I’d get it out o’ them, I’d get it out o’ them,” he told himself over and over again after the first thrill of awe at the shrill sound from the waterfall. “Whether there’s anything serious happened to Hal or not, I believe some o’ those boys know something about it. Wait till to-morrow morning, and I’ll find out.”

Pepper nodded his head and shook his fist determinedly as he spoke. He was talking vehemently now, articulating his words without reserve, for they had approached so near the noisy falls that he could not hear himself speak.

But he was interrupted by another scream from the cataract. This was no louder than the last preceding, but it was more thrilling, for they were closer. Every member of the searching party would have declared that only a human throat could send forth such a sound.

They approached close to the cataract and gazed helplessly into the water. What could they do? It was a most astonishing and unfathomable mystery. All they could do was stand and look and listen.

Presently Dr. Byrd pulled a sleeve of each of his companions and motioned them to follow him.

They started down the stream again, but soon they were halted involuntarily by another wailing cry from the same source. Dr. Byrd did not turn back, however, but went on after a moment’s hesitation. The others followed.

Beyond the reach of the deafening noise of the waterfall, the doctor stopped and began to discuss the affair with trembling, hollow voice, his face showing white in the rays of the lanterns. He was not frightened, but the circumstances were unusual enough to unstring his nerves.

The rest were similarly affected, even Pepper experiencing a weakening of his knees as a result of the last two screams.

“What in the world does that mean?” gasped the doctor. “There it goes again,” as another scream, somewhat fainter than the last two, reached their ears. “Can’t one of you offer a possible explanation?”

“Maybe it’s a mountain lion or a lynx,” suggested Pepper. “You know there’s said to be a few in the mountains around here.”

“That’s a brilliant idea,” exclaimed Dr. Byrd enthusiastically, “or rather, it’s a commonsense explanation that ought to have occurred to any blockhead. Hence, what are the rest of us? I feel better all of a sudden. But no! If it is a panther—”

He hesitated.

“What then?” inquired Mr. Frankland.

“It may explain, may it not, what became of Hal?” replied the doctor slowly.

“You mean that the beast killed him?” inquired Mr. Porter.

“Yes.”

“No, no, that would have been impossible. Such a tragedy could not have escaped the notice of some of us. Moreover, there’d have been some traces left—blood, broken bushes, and maybe torn-up sod.”

“Yes, that’s true,” admitted the doctor. “But what’s become of the boy? I’d face a hundred panthers to get Hal back safe. My! there’s that scream again. It doesn’t sound like a wild animal. It’s almost human.”

“If it’s a panther or a lynx, where do you suppose it is?” inquired Mr. Frankland, addressing Pepper.

“In the rocks near the waterfall somewhere,” replied Pepper.

“I should think we’d have seen him or have been able to locate him when we were up close,” reasoned the doctor.

“It’s too dark up there—the fall’s right in the shadow of the mountain. And the noise o’ the water confuses things so you can’t tell just where the scream comes from.”

“I can’t believe any wild animal makes that noise, and I’m in favor of making further investigation,” said Dr. Byrd.

“I’m with you on that,” Mr. Frankland announced; “but before we proceed, I propose we arm ourselves against a possible encounter.”

“How?” Mr. Porter asked.

“With clubs. Four of us ought to beat off a panther with good strong heavy sticks.”

“It’s a wise precaution,” the doctor approved. “Let’s get busy.”

They proceeded to a near-by thicket and there found a number of young trees that suited their purpose admirably. Like the Boy Scouts, they too were supplied with large sharp jackknives, and in ten minutes each was armed with a club that seemed formidable enough to break the skull of a lion.

Then they turned again toward the cataract, advancing close to it and flashing their lanterns over the big tumble of water and the adjoining piles of rocks. But they discovered nothing that suggested an explanation of the mystery. The screams continued to come, seemingly from the fall, but it was ridiculous to believe that any living being, human or beast, could exist in that flood and, with clear, strong lungs, emit such wailing sounds of distress.

For fifteen minutes they watched and listened, while the cries continued to come at intervals of a minute or two. Finally, since the examination of the fall and the rocks near it produced no result, Dr. Byrd began to give all his attention to the cries themselves.

After close and careful listening he was certain he could distinguish a feature in the cries that had not attracted his notice before. He strained every nerve in order to catch the sounds more distinctly. Observing his attitude as he leaned forward and put his hand cup-shaped behind his ear, the other men followed his example and soon they too were certain they could make out a single word uttered by a human voice.

“Help!”

It seemed to come more clearly now and was repeated several times in rapid succession. The eager listeners turned to each other and nodded their heads significantly; then they listened again as the call was repeated. But only the one word could they make out.

“Where are you, Hal?”

Dr. Byrd shouted this answer to the appeal, but his voice was heavy, attuned almost to the noise of the waterfall, and could hardly have been heard by the person in distress. Then Mr. Frankland and Pepper measured the strength of their vocal organs against the noise of the cataract with little better result. But Mr. Porter had a high, shrill voice, and when he sang out with all his strength “Oh, Hal, where are you?” there was a general feeling among them that the boy must have heard it. Then they listened again.

A reply was surely coming. It was not a single word, but several that issued from the waterfall this time. They seemed to come in the form of a sentence, but only one was heard distinctly enough to be recognized. That word was understood by all. It was “behind.”

“Behind what?” was the question that naturally came to the minds of the listeners. But before they could conjecture an answer, there came a startling interruption that drove all thought of the mystery of the cataract momentarily from their minds.

Happening to turn his face away from the waterfall, the doctor beheld the dim outlines of a small human figure twenty feet away. Believing it to be Hal, he ran joyfully toward the boy and was followed by the other men. The object of their interest did not move. In a moment they were close to him and holding their lanterns before his face.

But the boy was not Hal. It was Frank Bowler, supposed to be back at Lakefarm and fast asleep in the dormitory. And his countenance could hardly have been whiter if it had been coated with white enamel. Moreover, he was trembling as if he had seen a ghost.

“Frank, Frank, what is the matter? What does this mean?” cried Dr. Byrd; but he forgot that he was too near the cataract to carry on a conversation, and the boy did not understand him.

Just then there came another scream out of the roar of the waterfall, and Frank, the boastful, fell on his knees, shaking with terror.