"Of whom?" demanded Grace, getting quickly to her feet and hurrying to Hippy. "I don't know, but I saw several men about two hundred yards from here. They are creeping up on the camp. Hurry! Get the girls into the cave. I will keep watch here until you get safely to the cave." It was but a few minutes later when the Overland girls filed silently from their camp and headed for the cave. Hippy, rifle in hand, halted just outside the camp and waited. He did not have long to wait. A burst of rifle fire woke the mountain echoes, but, being out of the range of fire, he merely crouched down and waited to see what the attackers would do. In the cave, the Overland girls were peering from the opening, but, by agreement, not a shot was fired by them or by Lieutenant Wingate. The shooting kept up briskly for several minutes, then died away, and silence settled over the scene. Hippy remained near the camp so long that the girls began to feel concerned for him. This was dispelled nearly half an hour later when they discovered him, well bent over to hide his movements, running towards them. "Whew! They didn't do a thing to our tents. Shot them full of holes," he exclaimed. "They are going through everything and they're getting worried, judging from what I overheard. We played a neat trick on them," chuckled the lieutenant. "Don't crow," advised Emma Dean. "It isn't daylight yet. I will con-centrate. I con-centrated all the time you were away, and you came back, didn't you?" "'Con-centrate' on those ruffians and drive them away; 'con-centrate' on Tom Gray; 'con-centrate' on the Mystery Man--'con-centrate' on anybody, but for the love of Mike don't let loose any of that 'imponderable quantity' on me," begged Lieutenant Wingate. Hippy advised the girls to lie down on their blankets and try to sleep, saying that he would keep awake and watch at the cave entrance, but none of them felt the slightest desire for sleep, especially when the rifle fire opened up again. They wondered if the attackers were shooting at shadows. Not more than a dozen shots were fired and these at intervals, after which there was no more shooting during the rest of the night. At daybreak Hippy dozed off, first nodding to Nora to take the watch for him, which she did. The others of the party were sitting on the rocky floor of the cave leaning against the wall, also dozing. Nora, for a short time, sat watching her husband who was snoring loudly; then she got up and peered out at the reddening sky. Unthinkingly, she stepped from the cave and stood inhaling deeply of the fragrant morning air. Nora suddenly uttered a cry and clapped a hand to her left cheek. At the same instant, it seemed, the report of a rifle woke the echoes. Hippy, awake and on his feet in an instant, jerked Nora back into the cave, but not before a bullet had flattened itself against the rocks close to his head.