Slade sent one of his men springing up the side of the arroyo. The Navaho glanced over the edge of the bank toward the cliff house and dashed obliquely back into the dry channel, his hand twisting in swift signs. Slade held on up the arroyo. Near the mouth of Hell Canon he flung himself off and motioned Lennon to follow. The old Navaho led the way up the side of the reservoir, with Pete a close second. Near the top the leaders flattened down to crawl over the round of the ancient dam. The others crept after them. A muttered command from Slade had kept Lennon in the rear. But a sudden fresh outburst of shots cut short his frightful suspense. The Apaches had neither abandoned their attack nor had they yet captured the cliff house. Elation, mingled with renewed fear for the girls, sent Lennon scrambling up beside the leaders. He came to where they were peering over the crest of the dam. Slade growled a command for the fool tenderfoot to get down out of sight. But after Lennon's first look across the top of the embankment main force would have been required to drag him back. He had already guessed that Pete had stolen away down into the lower canon, unknown to the Apaches. The only other explanation was that the Navaho had been posted as guard at the cross cliff. This was improbable, as the only need for watchers was to help in-comers up the otherwise impassable barrier. That Pete had not been missed was evident from the failure of the Apaches to oppose the rush of the rescuers up the valley. The mystery of how Cochise hoped to take the cliff house became clear to Lennon at the first glance. The ancient stronghold was less than half a mile away from the reservoir. In the crystal-clear air Lennon made out a crooked line of poles and what appeared to be three or four sacks of corn lying upon the cliff foot. Above these objects eight or nine Apaches were raising a long ladder of spliced poles against the face of the rock wall. The fallen poles were the shattered remains of a first ladder that had collapsed. The ladder raisers were protected in their work by the incessant shooting of the other members of the band. From a crescent of positions well out in the valley the riflemen poured a cross-fire of bullets into all the openings of the cliff house. The Indian at the nearest end of the crescent lay not more than a hundred yards beyond the far side of the reservoir. Even as Lennon grasped the plan of attack, the heavy-butted ladder came to an upright position directly under the main doorway of the cliff house. On the instant a pair of nimble Apaches scrambled to the top, dragging with them a shorter ladder. They hoisted it above them and spliced its foot to the head of the main one.