A little later Joe started to take a motion picture of a small animal that darted across the river bed, but cried out in disgust. "A pesky fly got in front of the lens," the youth explained. "Looked as big as an elephant." "One scene ruined," laughed the archæologist. "But you'll have to get used to that." The adventurers stopped here and there to rest and sip a small amount of water. Then they would hike on, always on the lookout for the unusual. They had just rounded the corner of a tall, cone-shaped peak when Joe stopped and pointed to the sand near by. Dr. Kirshner's jaw dropped in surprise. "Footprints!" he cried. "Human footprints!" He had hardly uttered the words when there came a chorus of yells from behind a large rock. A moment later ten or twelve rough-looking Arabs darted out and surrounded the Americans. The natives at once disarmed the whites by sheer force and then displayed long knives threateningly. The Arabs chattered ominous words, which caused Dr. Kirshner to start in alarm and fear. "We are being captured!" he exclaimed excitedly. "These Arabs are hired by the two thieves who stole Fekmah's map!" CHAPTER XXII The Cave of Treasure At Dr. Kirshner's dread explanation, Joe cried out in surprise and fear. "Captured!" he mumbled in a strange voice. "Find out how long they are going to keep us." The scientist put the question before the Arabs, who laughed mockingly. "Until the treasures have all been taken from the hidden cave," they replied in the native language. Dr. Kirshner could hardly believe his ears. "Then--the riches have been found?" he demanded. "Yes. And we are to keep you away. We know not how long it will be. If you act right, we will treat you well. But if you try to get away you will be severely punished." "Where are you taking us?" For answer the Arabs only laughed. "What do you think of it?" asked Joe, after his friend had translated the natives' words. Dr. Kirshner shook his head. "Looks like we're not going to get back to camp today," he said gravely. "Worst thing is, these rascals may hunt out our friends and capture them also. If we could just leave some word that would give them a hint to be on the lookout----" The two Americans were forced along the narrow edge of a deep canyon, and more than once they felt that they were but an inch from death. Their tempers were thoroughly aroused, but they knew that they had no chance against such a horde. "These fellows are a bit different from American roughnecks," Dr. Kirshner said. "Arabs would not hesitate to stick a knife through you if not satisfied with your actions, but our own countrymen would ordinarily think twice before doing such a thing." The two explorers were in the midst of the group, with swarthy natives on each side of them. To attempt to break loose would indeed be futile. "I wonder if we will be taken near the hidden riches?" muttered Joe, gazing ahead at the distant country.