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." CHAPTER XXVII The Hidden Treasure Bob looked at his father in surprise. "What do you mean?" he asked. "Simply that no one is there to drive away now," was the reply. "We have captured all of the Arabs--even the two thieves who stole Fekmah's map. And I might add that we have located the hidden treasure."