FOR a distance of several hundred yards the country remained comparatively level, although dotted with huge rocks. Then mountains loomed up before them, and they found it necessary to travel slower.

Bob was followed by about fifteen Tuareg warriors, all magnificent specimens of “desert knights.” Each man was armed with a rifle which, although inferior to Bob’s high-velocity type, could do much damage.

Bob was almost certain he could find the way without the small sketch map he had made from the top of the tall peak the night before. But he had the map in his pocket and intended to consult it if necessary.

Breathlessly he led the way through the rough country and at last came to the spot where his father and friends had been captured by the Arabs.

From then on, finding the way would be easy, the youth thought, for he had only to move toward an odd formation of twin peaks that loomed up above the other mountains in the distance. The cave in which those captured were probably being held was along the side of those tall double peaks.

To make sure of this, Bob got out the map and scrutinized it closely. Then, satisfied that he was right, he dashed forward, the Tuaregs at his heels.

The way now led up the side of a large hill. There was a break just to one side of the path, and the rescuers could look down to the foot of a deep gorge. Bob kept his dromedary as far away from the brink as possible, to do away with the grim possibility of the ground giving way from under his camel’s feet.

Finally, after trudging over a high plateau, they began climbing the base of the twin peaks. At first the ascent was very gradual, but in a short time the path curved upward around the side of the mountain.

“Getting there, all right,” observed Bob, as he noticed that they were now several hundred feet above the plateau.

At last they came to the top of a wide ledge, from which they could look out over scores of miles of rugged country. As the shelf began to narrow, Bob called a halt.

He took out the paper of native words and told the Tuaregs that they were now near the cave in which were his father and friends. It would only be necessary to round a corner before coming to its entrance.

But first he divided the group of natives into two sections. One, under the command of the chieftain, was to move on around the ledge to the cave from the west. The other, led by himself, would climb the steep side of the mountain and walk on above to the other side of the cavern. Then they would meet at the entrance and surround the Arabs and release the prisoners.

When Bob gave the word, the Tuaregs swung into action. Those in his group followed him up the cliff to the brink, while the men under the chieftain began moving around the ledge.

It was a dangerous climb up the steep side of the mountain, but at last Bob pulled himself up to another ledge about fifty feet above the lower one. Then he led the way several rods along its surface. When he thought they had passed beyond the entrance to the cave, he led the descent to the lower shelf.

A moment later he saw that he had miscalculated. He had not gone far enough beyond the cavern to escape the wary eyes of the Arabs who were stationed as guards.

“Caught!” he exclaimed. “Caught square!”

Four Arabs were sitting out in front, and they were on their feet instantly as their eyes fell on Bob. The latter was no more than twenty-five feet away from them, much nearer than he had expected to be.

The Arabs’ rifles were standing against the wall of rock near the cave. But before the men could get to them, Bob rushed forward. With a wild shout he kicked the rifles away and dashed into the cavern.

Startled exclamations—exclamations of joy, surprise, happiness—came to the youth’s ears, and he realized that he had at last found his father, Joe, and the others.

“Bob! You here!” cried Mr. Holton in wild excitement.

“You old rascal! I knew you’d get us out!” came from Dr. Kirshner.

But there was no time for that. Danger was at hand.

“Quick!” he commanded. “Hide. Here, take my rifle, somebody. I’ll use my pistol. There’s no time to lose!”

The words were scarcely out of his mouth when the four Arabs darted inside the cave and made for the captives and their new enemy. They would not be beaten so easily!

With a terrific crack to the chin, Bob sent the foremost Arab to the ground. The other three men were making for the prisoners in the back of the cave.

Mr. Holton had taken Bob’s rifle and was by the youth’s side looking for other Arabs.

Suddenly Bob noticed that the man whom he had knocked down was getting to his feet and making for the rifles not far away.

Without hesitating a moment, the youth dashed out of the cave and directed a stinging blow to the Arab’s nose. The latter staggered a moment at the edge of the cliff, and then, to the horror of the two Americans, fell backwards over the cliff.

Bob gave a cry of regret. Despite the fact that the Arab was an enemy, the young man did not wish to send him to his death.

Mr. Holton had also been touched deeply.

“You—you shouldn’t have done that,” he muttered. “But—it couldn’t have been helped.”

Now a chorus of shouts and yells rent the air, and the Tuaregs rushed into the cave. To the surprise and relief of the Americans, they had captured the two thieves who stole Fekmah’s map. Where had they found them?

Mr. Holton, Dr. Kirshner, and the other former prisoners were taken aback at sight of the natives. At first they thought them other enemies. Bob soon gave an explanation.

The thieves were searched for Fekmah’s map, but the latter was not found.

Meanwhile a struggle was taking place at the rear of the cave.

Joe in particular attracted Bob’s attention. The former youth was grappling with a large, powerful fellow, who was vainly trying to choke his young enemy.

“Joe’s sure a fighter,” remarked Bob, as he and his father looked on for a moment.

“We had better help him, though,” Mr. Holton said. “Come on.”

But a second later they saw that this would be unnecessary, for Joe had suddenly jerked away and sent his fist with all force into the Arab’s jaw, knocking him out.

“Great work!” commended Mr. Holton. “That fellow was dangerous.”

The two remaining Arabs saw that they had no chance against so many, and they surrendered without a struggle.

“Now tell us all about it,” urged Dr. Kirshner, speaking to Bob. “We want to know how you managed to engage the aid of these Tuaregs.”

Briefly the youth outlined his adventures since escaping from the Arabs the day before. He told of climbing to the top of the peak, of saving the Tuareg chieftain from death, and of getting the paper of Tuareg words.

“That’s all,” he finished. “Only these natives came up here with me to get you out of the clutches of these Arabs.”

“A wonderful demonstration of ingenuity,” breathed Mr. Lewis. “We expected you all the time. Knew you’d find some way.”

“But our greatest work is yet before us,” Bob said. “We must drive the Arabs from the hidden treasure—if we can locate it.”

“No,” came from Mr. Holton, “we won’t need to do that.”