Tad mounted his own horse and galloped along at the base of the rocks, well shielded from any one who might be hiding further back in the mountains. The Pony Rider Boy's mind was working rapidly. He was forming a plan of campaign. He was inclined to agree with the theory of Professor Zepplin. Still, theories would not help them at this critical moment. They must protect themselves and at once if they expected to get out alive. One course was plainly open to them. They could mount their ponies and ride out over the plains at a gallop and perhaps escape. However, this plan was rather risky. Besides, Tad did not like the idea of running away.

"No, we've got to do something else," he declared out loud. "I have it!" The boy brought his pony up standing and gazed off over the plain to a point about a quarter of a mile beyond, where the plain rolled into a hollow, a "hog hollow" as it was called down there.

Butler galloped back to where his companions were standing anxiously awaiting him.

"We are wasting time, Tad," cried the professor as the lad rode up.

"It is my opinion that we had better ride into that canyon there and make camp in some secluded spot where we shall not be easily found."

"I am afraid that won't help us any, Professor," said Tad. "How could we expect to hide ourselves in there so completely that a mountaineer would not find us? No, sir, it is my opinion that our only safety lies out there in the open, at least for the rest of the afternoon and the night."

"What, ride out there to be shot up again?" demanded Stacy. "No, sir, not for Stacy Brown! I've been shot up once. I don't propose to make a bull's-eye of myself again."

"Stacy is right, boys. It would be foolishness to follow such a course and---"

"Wait till you hear my plan, sir," urged Butler.

"We will hear it. Proceed."

"Out yonder about a quarter of a mile from the base of the rocks is a depression in the plain. If we can reach it we shall be safe---"

"Yes, if we can reach it," repeated Ned.

"In doing so we should be shot in all probability," objected Professor Zepplin.

"I think not, sir."

"Explain what you mean?"

"From the position occupied by the man or men when they fired at us out there, I am sure they could not see us were we to follow the course I went out on just now. If you will ride down to the edge of the foothills with me and wait there, I will gallop out and prove my theory."

"What do you mean?" questioned the professor.

"I will see if I can draw their fire," answered Tad.

Professor Zepplin shook his head.

"Too risky!"

"It certainly is risky to stay here. Listen, sir. If that man wants to get us he surely will be creeping down on our position before long.

We are in greater peril here, where we can't see anything on one side of us, than we would be out there where we have an un.o.bstructed view on all sides. My plan is to make camp out in the hollow; then we will place a guard over the camp, keeping a sharp watch all through the night. By morning we'll be able to find out what is in the wind."

"I won't move a step," declared Stacy stubbornly.

"You will do whatever seems best to the rest of us," answered the professor sternly. Then, after a moment's thought, he added, "I am inclined, upon second thought, to agree with Tad. We will try the plan."

"Good. Follow me. Get that pony, Chunky. I told you once before to catch him. We'll be in a fine mess if you lose your mount."

"I'd rather lose my mount than to lose my precious life," answered the fat boy surlily.

By this time the others were taking to their saddles. The faces of all wore serious expressions. They had not looked for anything quite so lively as this. It was not the first time the Pony Rider Boys had smelled powder when the powder was being expended on them, but they liked it none the better for past experiences.

Stacy's cheek was bleeding again. He was holding his handkerchief to the wound and his face was a little paler than usual.

"Buck up!" commanded Ned. "You're not going to show the white feather, are you?"

"No, it's a red feather I'm showing," wailed the fat boy.

"Forward!" ordered Butler. "Get up, Chunky!"

The party moved off, keeping close to the rocks, Tad now and then casting apprehensive glances up to their tops. He was not wholly satisfied that they were out of range of the bullets. The man who had been firing at them, too, was practically a dead shot.

"Now spread out," commanded Tad after they bad reached the point where he previously had halted. "Don't shout, but when I wave my hand, ride fast for the hollow. I'll be all right; don't worry about me."

With that the lad galloped leisurely out on the plain, his back to the mountains. It was a bold thing to do. Deep down in his heart the Pony Rider Boy expected every second to bear a bullet scream over his head, providing he was fortunate enough not to stop the bullet with his body. Not a shot greeted his bold act.

Tad rode on, finally disappearing in the "hog hollow." A few moments later he rode up the ridge, waving his hands for them to come on.

Professor Zepplin started out at once, followed by the others of his party, Stacy this time well up toward the front of the line. For reasons of his own he did not care to drag behind. If there was to be any shooting he wanted to be as far away from it as possible.

The trip was made at a fast gallop and without incident, the party reaching the hollow without having drawn a shot from the enemy.

"It is my opinion," declared the professor, "that, whoever our enemy may be, he has discovered that he has made a mistake."

Tad shook his head.

"I don't think we would be safe in taking that for granted. He did not see us, but he will be on hand before long. I'm going back there before he does see us. If he starts any more shooting you all lie low."

"Where are you going?" demanded the professor.

"On a scouting trip."

"I cannot consent to any such foolhardy business," answered Professor Zepplin sternly.

"It is not foolhardy. We've got to clear up this mystery. Don't you see, we shan't dare go any farther---we simply cannot go into the mountains knowing there is some one there waiting to riddle us the first time he gets a clear sight at us?"

"But what do you propose to do?"

"I don't know, beyond finding out what is up."

"Yes, let him go," urged Stacy. "He's looking for trouble. I'm the only one who has had any experience thus far. It's time some one else made a mark of himself."

"I was thinking of taking you with me," laughed Tad.

"No, you don't! Not if I see you coming," objected Stacy.

"Yes, take him along," urged Ned.

"No, I think I'll take you, the Professor being willing," answered Tad nodding at Rector.

Ned stopped smiling, gazing at Tad to see whether the latter were in earnest. Tad was.