"It has another weak point. It runs on caterpillar tracks--that is, really, on wheels turning inside an endless belt that gives a wider basis of support. But if any sizable, hard object finds its way between wheel and track--" He paused significantly, and the bird-girl's eyes met his in a luminous dawn of understanding and hope. They had no trouble finding the trail of the panzer. As he scanned those yard-wide tracks, paralleling each other ten feet apart, Torcred's grip tightened on his T-beam; it did not seem quite so thick and heavy now, against all those tons of rolling metal might. But he had boasted recklessly, and he was going through with it if it killed him. VI Stealthily they crept along the trail in the direction the monster had taken, lying prone to peer with immense caution over the wave-crest of each dune it had breached in crossing. Beyond the sixth or the seventh crest, it was there. Lying still in a hollow of the sand, its gray paint blending with the drab earth to make it almost invisible from the air--and its radar alarms, no doubt, keeping watch for any moving threat. Encased in armor almost to the ground, over the great treads, and its three rounded turrets astare with guns. At first glimpse Torcred jerked his head back like the extinct land reptile whose namesake he was. His palms grew sweaty and his insides quivered. If he had been alone, he might have slid quietly down the slope and stolen away, leaving his T-beam behind him. But he heard Ladna's quickened breathing at his back, and knew she knew he had seen the panzer. Before he could check her she had wriggled up beside him and peered over the edge. When she drew back her face was shades paler beneath its peeling sunburn. Her lips framed words: "Are you going to try?" Torcred nodded, jaw set. "You stay here," he hissed, and, gripping his weapon, began to slither over the crest of the dune. When he was on the far side and nothing had happened, he felt reasonably sure he had passed below the horizon of its radar. But he continued to crawl, eyes fixed on the giant enemy, watching for the first stir of motion about it that would be followed by a smoky blast of death. Halfway there--Almost there--He reached the edge of the panzer's shadow. Then he distinctly heard a low burring sound from inside it. Alarm! A magnetic mine detector, probably, tripped by the metal beam; Torcred realized that even as he flung himself forward in a scrambling rush that carried him the rest of the way. The driver must have been alert. Even as Torcred caught himself with a hand against the gray steel flank, the muffled motor throbbed into life and the great machine surged forward. Torcred ran stooping beside it, eyes measuring the gap between armored housing and racing tread. Seconds to live if he missed--already his lungs were bursting and the great gray side was slipping past. With both hands he drove the T-beam straight into that gap.