Linda nodded. "It's presence has been known, of course," she replied. "It leads to an underground cavern that stretches for miles under the surface. It's the burial place of the first dynasty Martians. But there are many such places below the Red Desert country. Always it has been thought they contained nothing of value." They reached the bottom level and stood staring out before them. Where the floor of the desert above had been red in color, the surface here was ochre, a dull uncertain floor that gave off a radiance of its own and illuminated the underground cavern with a faint unreal glow. The grotto stretched in three directions as far as the light permitted them to see. At intervals of every twenty feet or so, large rectangular blocks, ten to fifteen feet high and twelve feet long, dotted the expanse. In a way the place looked like a vast apiary. "Each one is a grave," Linda said quietly. "The block, of course, is only a marker. The crypt is lower down." Jimmy scowled. "And one of those crypts contains the figurines, eh? Like looking for a needle in a haystack." She gripped his arm. "We've got to find the right one before Garth. We've got to, do you understand! He's somewhere down here now, with those two hirelings of his. When--if--we do find it, this will destroy them." She pressed a short tube in Jimmy's hands. Like three sleep-walkers, they paced slowly out among the stone blocks. And now Jimmy realized the proportions of the task they had set themselves to do. Each of the blocks was equipped with a vault-like door of massive weight and size, surrounded by a panel of those strange hieroglyphics, and with an intricate series of bizarre lock dials on its surface. The blocks looked exactly the same. Above them in the dimness of the ceiling a heavy whirring sounded, and at intervals a curious bird-like creature with pointed wings and a weazened human face swooped down to be momentarily visible in the half light. "_Sarkonivals_," Linda said shortly. "The early Martians were superstitious of them and transported them here to guard the burial grounds. They must feed on a variety of moss that grows down here." They moved on. The rows of burial blocks seemed endless. Jimmy came to a halt. "We're getting no place fast," he said. "Have you no clue at all as to which block it might be?" Linda shook her head. Hanley was staring up above him, apparently fascinated by the strange flying creatures. "You know," he said slowly, "I read about those _sarkonivals_ once. They always fly in groups of an even twenty, save when some atmospheric disturbance causes them to alter their formation." He pointed upward. "They _are_ all in groups of twenty except over that block over there. Above that they seem to be in confusion." Jimmy followed his gaze and frowned thoughtfully. He paced forward to the block in question, stood there watching the movements of the _sarkonivals_.