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.