Down a little valley between two high mountains rode four explorers, their eager eyes penetrating every crevice and notch in the mountainous country about them. High-power binoculars were turned upon every level stretch, rifles were fired at regular intervals, voices were brought to new swells. It was a search that under ordinary circumstances would have brought Dr. Kirshner and Joe back in a very short time. Finally, after the searchers had been out several hours and darkness was beginning to fall, Mr. Lewis stopped and buried his face in his hands. He realized that defeat was staring them in the face. "Guess they're really lost," sighed Bob Holton, his face extremely sober. "Or else something has happened to them," added Fekmah in a voice that he tried to keep steady. Mr. Lewis said nothing, but he feared all too much that the Arab was right. And yet, he reasoned, they were likely to be very careful and not take chances. Still that would not prevent nature or wild tribes from harming them. Mr. Holton, however, was very optimistic. He believed that, despite the length of their stay, the two were safe. Perhaps they had fallen asleep from exhaustion or had wandered farther away than they had intended and were forced to spend the night in the mountains. Tishmak had been left at the camp, as it was thought best to have someone there in case the archæologist and Joe should return while the searchers were gone. "We're a long distance from camp," said Mr. Lewis, as the searchers sat on their camels at the brink of a deep gully. "Shall we try to get back tonight?" "I'm in favor of it," returned Mr. Holton impatiently. "Of course we left word with Tishmak that we might spend the night away, but he may be greatly worried. Then, too, he might not be safe there alone." The others thought this good advice, and turned the dromedaries back up the lane. They could possibly get half of the way there before the darkness would halt them. Then the moon would probably furnish sufficient light to continue. "Here's hoping they will be at camp when we get there," said Bob. But Tishmak was the only one who greeted them when finally they rode wearily up to the tent. The guide had fully expected to see the lost ones return with the others, and his face wore an anxious look when he saw that their search had been in vain. Fekmah immediately related their past experiences, concluding by asking what Tishmak thought had happened to them.