CHAPTER I

A MYSTERIOUS VISITOR

"Boys! B-o-y-s!"

There was no response to the imperative summons.

Professor Zepplin sat up in his cot, listening intently. Something had awakened him suddenly, but just what he was unable to decide.

"Be quiet over there, young men," he admonished, adding in a lower tone, "I'm sure I heard some one moving about."

The camp of the Pony Rider Boys lay wrapped in darkness, the camp-fire having long since died out. Not a sound disturbed the stillness of the night save the soft murmurings of the foliage, stirred in a gentle breeze that was drifting in from the southwest.

The Professor climbed from his cot, and, without waiting to draw on his clothes, stepped outside. He stood listening in front of his tent for several minutes, but heard nothing of a disturbing nature.

"I believe those young rascals are up to some of their pranks—either that, or I have been having bad dreams. While I'm up I might as well make sure," he decided, tip-toeing to the tent occupied by Tad Butler and Walter Perkins.

Both were apparently sleeping soundly, while in an adjoining tent Ned Rector and Stacy Brown were breathing regularly, sleeping the sleep that naturally comes after a day in the saddle over the rugged, uneven slopes of the Ozark Mountains.

Professor Zepplin uttered something that sounded not unlike an Indian's grunt of disgust.

"Dreams!" he decided sharply. "I should not have eaten that pie last night. Pie doesn't seem to trouble those boys in the least, but it certainly has a bad effect on my digestive apparatus."

Having thus delivered himself of his opinion on the value of pie as a bedtime food, the scientist trotted back to his tent, his teeth chattering and shoulders shrugging, for the mountain air was chill and the Professor was clad only in his pajamas.

No sooner had he settled himself between his comforting blankets, however, than he suddenly started up again with a muttered exclamation.

"I knew it! I told you so!"

This time there could be no doubt. He plainly heard a dry twig snap near by; whether it were under the weight of man or beast, he did not know.

"There is something out there. It couldn't have been the pie after all. I'm going to find out what it is before I get back into this bed again," he decided firmly, slipping quietly from under the covers and peering out through the half closed flap of his tent.

As before, all was silence, the drowsy, indistinct voices of the night passing almost without notice.

But Professor Zepplin instead of waiting where he was, reached for his revolver and then strode boldly out into the open space in front of the tents, determined to solve the mystery, and, if possible, without waking the boys.

The reader no doubt already has recognized in the four boys sleeping in the little weather-beaten tents the same lads who some time before had started off for a vacation in the mountains where they hunted the cougar and the bobcat, the thrilling adventures met with on that journey having been related in a former volume entitled, "THE PONY RIDER BOYS IN THE ROCKIES."

They will be remembered, too, as the lads who, in "THE PONY RIDER BOYS IN TEXAS," crossed the plains on a cattle drive, during the course of which Tad Butler bravely saved the life of the Chinese cook, by plunging into a swollen torrent; and later, saved a large part of the great herd, himself being nearly trampled to death in a wild stampede of the cattle.

It will be recalled also, how Tad Butler and his companions, after many strange and startling experiences, solved the veiled riddle of the plains and laid the ghost of the old church of San Miguel, for all time.

The stirring adventures of "THE PONY RIDER BOYS IN MONTANA," too, are still fresh in the minds of those who have followed the fortunes of the four lads since they first started out on their journeyings.

It will be recalled that in the latter story the lads experienced the thrill of being in a real battle between the cowboys and the sheep herders on the free-grass range of the north; how Tad Butler was captured by the Blackfeet Indians, and how, with the help of an Indian maiden, he managed to make his escape.

It will also be remembered that Tad was able to rescue another lad who, like himself, had been taken by the Blackfeet, and to return the boy to his father, none the worse for his exciting experiences. It will be recalled as well, how Tad Butler through his own efforts solved the mystery of the old Custer trail—a mystery that had perplexed and annoyed the ranchers along the historic trail for many months.

And now they were once more in the saddle, having chosen the Ozark Mountains in southwestern Missouri as the scene of their next explorations.

With them they carried a pack train of four mules, these being best adapted to packing the boys' belongings over the rugged mountains. For their guide they had engaged a full-blooded Shawnee Indian named Joe Hawk, known among his people as Eagle-eye, making a party of six, with eight head of stock in all.

At the time of the beginning of this narrative the Pony Riders were encamped on a fork of the White River some three days out from Springfield. Joe Hawk had asked permission to leave the party for the night to pay a visit to a fellow-tribesman who lived somewhere in the mountains to the west of them.

On second thought it occurred to Professor Zepplin that perhaps it might have been Joe, or Eagle-eye, as the boys had decided to call the Indian, whom he had heard skulking about the camp.

"Eagle-eye," he called softly.

There was no response, so the Professor, gripping his gun resolutely, crept along toward the opposite side of the camp where the noise had seemed to come from. So quietly had he moved that he made scarcely a sound, until suddenly there came a commotion that more than made up for the noise he had so successfully avoided before.

Stacy Brown, with his usual forgetfulness, had left his saddle in the middle of the camp. The Professor caught his toe on the obstruction, measuring his length on the ground instantly, where he floundered about for a few seconds.

"Instead of discovering the other fellow, I think I am discovering myself," he growled, scrambling to his feet, gingerly rubbing a knee.

Now the Professor walked with a distinct limp, while his bare feet seemed to pick up every sharp pebble in camp, all of which added to his discomfort.

"I'd make a nice sort of scout," he muttered. "Everybody within a mile of me would know I was coming even before I got started, I guess—"

The Professor suddenly cut short his words, and crouched down close to the ground. He thought he heard something ahead and a little to the right of him.

"Who's there?" he demanded.

No answer being made to his inquiry, he gripped his gun more firmly and crawled cautiously toward the spot where he thought he had heard some one moving. The night was so dark that he could make nothing out of the shadows about him, being obliged therefore to trust entirely to his sense of hearing.

Now he was certain that some one was in camp who had no business there, for the sound of footsteps was plainly borne to his ears—cautious, catlike steps, as if the intruder were seeking to get away without attracting attention.

The Professor, determined to capture the intruder, getting down on all fours to avoid possible detection, made a wide detour so as to come up behind where the fellow seemed to be at that moment. After much labor he managed to reach the desired position.

The Professor straightened up to listen. He must be close upon the other by this time. But what was his chagrin to hear those same footsteps on the opposite side of the camp. Professor Zepplin by much effort had just come from the other side himself.

"Stupid!" he muttered. "I'll take no roundabout way this time. I'll go straight ahead and be as quiet about it as I can."

He did so. He moved straight across the camp ground, not forgetting the saddle which he carefully avoided, but narrowly missing falling over it a second time.

By the time he had crossed to his former position, the intruder had done likewise. Professor Zepplin dodged behind a tree.

By this time the scientist was beginning to feel a little worried. He could not understand what the other fellow's object might be. If it were robbery, the fellow certainly would desire to get away as quickly as possible, rather than remain when he knew that efforts were being made to capture him. If not plunder, what could be his purpose?

With suddenly formed determination, Professor Zepplin strode out from his hiding place, starting for the other side on a run.

The other man did the same, and the only result of the move was that their positions were exchanged.

Once more the Professor decided to try strategy and see if he could not come up behind his opponent.

At the same moment the visitor apparently decided to resort to the same tactics. They went in opposite directions, however, to carry out their purpose, and when each arrived at the place it was to find that the other was opposite him again.

The Professor's bare feet were in a sad state by this time, his pajamas were torn and his hands were worn tender from using them for feet when running along on all fours. At the same time his temper was wearing to a point of dangerous thinness. It was likely to break down the slender barrier that held it at almost any time.

Suddenly he realized that the intruder had been silent for some minutes, and the Professor decided that it was time he ceased thinking over his own troubles and paid more attention to what the other man was doing.

"Now, I wonder what he is up to," growled the scientist. "I believe he has given me the slip and gotten away. Here I've been dreaming for minutes. I'll slip some myself and see if I can't surprise him if he's there yet."

Once again he started across the camp ground, without resorting to any of his former tactics, other than to proceed with extreme caution, covering the intervening space with long, careful strides.

Reaching the rock, he paused to listen, but could hear nothing.

Gun ready for instant use, Professor Zepplin dashed around the corner of the rock, running plump into the arms of the fellow whom he had been so successfully dodging for the past twenty minutes.

So startled was the scientist that he dropped his revolver, throwing both arms about his antagonist. He was surprised at the slenderness of the fellow, though he quickly discovered that what the other lacked in bulk he easily made up for by his lithe, supple body and muscular arms.

Almost before Professor Zepplin had collected his wits sufficiently to make any sort of defense he found himself lying flat on his back, with his opponent sitting on top of him, both wrists pinioned to the ground in an iron grip.

There seemed to the Professor something strangely familiar about the figure that was holding him down so firmly, but he did not try to analyze the impression. He had other things to think of at that moment.

"I'll wait a second until he lets up ever so little, then, with my superior weight, I ought to be able to throw him—"

"I've got you this time. What do you mean by prowling about our camp at this time of the—"

"Wha—what—who—who—" exclaimed the Professor.

"What!" fairly shouted the other. "Who—who are you?"

"I'm Professor Zepplin. Who are you?"

"Oh, shucks! I'm Tad Butler," answered the boy, hastily releasing his prisoner, and, more crestfallen than he would have cared to admit, assisting the Professor to his feet.

"What do you mean, you young rascal?" demanded the Professor, grasping the boy by the shoulders and shaking him vigorously. "I say, what do you mean by playing such pranks on me as this? Why, I might have shot you. I—"

"You are wrong, Professor; I have not intentionally played pranks on you—"

"Yes you have—yes you have," fumed the Professor.

"I might accuse you of doing the same thing to me, only I know you didn't get up in the middle of the night to play hide and seek with a boy—"

"Then what does this mean? Answer me instantly!"

"I can do so easily. The fact is, I heard somebody prowling around. The slight noise awakened me—"

"I should think it might," snarled Professor Zepplin.

"And, without waiting to dress, I slipped out—"

"And led me a nice chase. Look at me. There isn't a spot on my body that isn't black and blue. And to think I've been running around here in my bare feet trying to catch you—"

"You haven't entirely. You were chasing the same thing that I was," answered Tad thoughtfully.

"What's that? What's that you say?"

"I mean that somebody was here—somebody who had no business to be here."

"You mean—"

"Yes, I mean that after I had been out here a few moments I distinctly heard two men. One of them, it appears, was yourself. Who the other was I don't know. He evidently got away. As I couldn't follow both of them, I chose you. You seemed to be the easiest one to catch. I was right, wasn't I?" laughed the boy, at the thought of the game they had been playing with each other.

"Somebody else here? I knew it, I knew it," exclaimed the Professor. "When I first came out you were sound asleep. I must have awakened you when I fell over the saddle out there. Who left that thing there for me to nearly break my neck on?" he demanded angrily.

"I guess it must be Chunky's saddle."

"Of course. I'll talk to him in the morning. I'm going to bed. I'll catch my death of cold."

CHAPTER II

A PACK MULE GOES OVER A CLIFF

Next morning the boys, assisted by Eagle-eye, had prepared the breakfast by the time the Professor had awakened. They took keen satisfaction in calling him for breakfast. Ordinarily they slept so late that the Professor had to turn them out by physical force.

"Anybody'd think you'd been keeping late hours, Professor," laughed Ned Rector.

"Perhaps I have," answered the scientist good naturedly. "But if so, I am not the only one of this party who has."

That the Professor's words held some meaning unknown to them the boys were fully aware. Tad had said nothing of his experiences of the previous night, so they did not think to turn to him for an explanation.

"I might as well tell you, young gentlemen, that there was some one prowling about this camp after we all were asleep last night—"

"What!" cried the Pony Riders in sudden surprise.

"Yes, that is true. Thaddeus and myself chased him around for nearly half an hour, but—"

All eyes were now turned on Tad, who was bending over his plate that they might not observe the grin that was spreading over his face despite the lad's effort to keep it down.

"O Tad, tell us all about it," urged Walter Perkins. "What was he, a bold robber or what?"

"I guess he must have been an 'Or What,'" suggested Stacy Brown wisely.

"Don't mind him. He's dreaming still. It's only his appetite that's here at the table. The rest of him is in bed asleep," jeered Ned Rector, with such a funny grimace that the boys laughed.

"Yes," answered Tad, looking up, "we ran around here in our pajamas until we found each other. Then we gave it up and went to bed."

"But who was it?" insisted Walter.

"It was an—"

"Now, never mind, Chunky. You are supposed to be asleep," admonished Ned, with a superior wave of his hand.

"I cannot say as to that," answered Tad. "I really don't think it amounted to so very much. Probably some prowler curious to know what sort of camp he had stumbled upon. I didn't lose any sleep over it after I got back to bed."

"Neither did Chunky," laughed Ned.

"Did you?" asked the fat boy sharply, turning the laugh on Ned.

"You remember what we were told in Springfield," said Walter.

"What was that?" asked the Professor.

"That a band of robbers had been causing considerable excitement in the Ozarks for several months past."

"Yes, you are right. I had forgotten that," nodded Professor Zepplin. "Stealing horses and other things."

"Yes."

"But it's all nonsense to think they would bother us," objected Ned. "We haven't anything that they would want."

"No, nor do we want them," replied Walter, with emphasis. "I guess we had better sleep on our rifles to-night."

"That will hardly be necessary," smiled the Professor.

"How about Eagle-eye?" asked Ned. "Didn't he hear anything?"

"Eagle-eye was away last night."

"Oh, yes, that's so. I had forgotten that."

"It might be a good idea to tell him about it," suggested Tad, glancing over at the Professor.

Professor Zepplin nodded his head.

"Eagle-eye, will you come here, please?" called Tad.

The Shawnee, who had been pottering about the camp-fire, strode over to them with his almost noiseless tread, and squatted on the ground near the breakfast table.

"There was somebody here last night, Eagle-eye," Tad informed him in an impressive voice.

The Shawnee nodded.

"Of course, you not having been here, you knew nothing about it, but to-night you'd better sleep with one eye open.

"Joe Hawk know," answered the Indian.

"Know what?" demanded the Professor sharply.

"Know Indian come last night," was the startling announcement.

"What's that? What's that, Eagle-eye? You mean yourself, I presume. You mean you came back. But that is not the point—"

The Indian shook his head with emphasis.

"Other Indian come."

Tad nodded at his companions as if to say, "I told you so."

Then the Shawnee did know more than he had seen fit to tell them?

"Tell us about it, Eagle-eye."

"Joe Hawk find trail of canoe on river at sun-up," answered the Indian tersely.

"A trail on the river?" demanded Stacy, suddenly breaking into uproarious laughter, which died away in an indistinct gurgle when he found the eyes of his companions fixed sternly upon him. "Funny place to find a trail," he muttered, threatening to indulge in another fit of merriment.

"I don't understand you, Eagle-eye," said the Professor. "You say you found the trail of a canoe on the river?"

"Yes."

"That sounds peculiar. I agree with Master Stacy that it is a most remarkable place to find a trail hours after. Perhaps you will explain."

Eagle-eye rose to his feet.

"Come. I show you."

All rose from the table, forgetful that they were eating their breakfast, and followed the guide down the steep bank to the river.

"There trail," he announced, pointing a long, bronzed finger at the edge of the water.

Tad stooped over, examining the shore critically.

"The Shawnee is right," he said, turning to the Professor.

"How do you know? What have you found?"

"There. You can see for yourself. It is distinctly marked—"

"What's marked?" demanded Stacy, pressing forward.

"You can see where the keel of a canoe has rested in the dirt there. The trail is ever so faint, but it is unmistakably there. See how it broadens out as it extends backward until it reaches the gravel in the stream."

"Moccasin tracks," grunted the guide.

"Where?" asked Walter, apprehensively.

"There," answered the Indian, pointing up the bank whence they had just come.

The boys looked at each other in wondering silence.

"What do you think is the meaning of the visit, Eagle-eye?" asked the Professor.

The Shawnee shrugged his shoulders.

"Mebby hungry."

"That is a sensible explanation of the visit," decided Professor Zepplin. "What other motive could an Indian have for a visit at that hour? There is no cause for alarm. But I wish if any more hungry ones pay us a visit, they would do so in the day time, so as not to interrupt my sleep."

"And mine," laughed Tad.

"Yah-hum," yawned Stacy, sleepily.

"I told you you weren't awake yet," growled Ned. "Let's all go back to our breakfast."

"I second the motion," laughed the Professor. "We are forgetting all about the inner man. And it is time we were getting on our way if we are to make any great progress to-day."

Anxious to be in the saddle again, the boys bounded up the bank and hastily finished their breakfast. While they were doing so the guide stoically busied himself with packing the cooking kits and loading the pack mules, so that by the time the lads were ready all save their own belongings had been stowed away.