The Terrapin waited only for moments; then he opened his throttle wide and sent the little combat car swerving into the heart of the herd. All around rolled rumbling iron giants; the clank of couplings, the roaring of unmuffled engines were deafening. A hooting of furious horns arose as the terrapin darted and zigzagged between the moving units of the herd. But there was no blaze of gunfire. "So we hunt them," Torcred flung over his shoulder at the breathless girl. "They can't shoot when we're in among them; we disable one and shelter behind it until the herd passes on...." The terrapin dashed through narrowing gaps, slowed and spurted again, as Torcred threaded his way skilfully on an oblique course across the roaring stream. At last he saw open ground ahead; he grinned exultantly and put on a final burst of speed that carried him into the clear. The little car swooped with a sickening rush into a shallow valley, and behind it thundering flashes leaped along the flank of the trailer herd and bullets exploded around or ricocheted screaming overhead. As he slowed to a more moderate pace under cover of the farther dunes, Torcred turned, still grinning, to the bird-girl. "That," he commented, "was the dangerous part." She shivered slightly. "I was afraid," she admitted candidly. "That's hardly as simple as attacking a mere crawling terrapin from the air, eh?" The girl turned her face away. "That was necessary, terrapin ... I passed my fledgling examination only two days ago; it was my second flight beyond the safety zone. The novice must defeat some machine of prey in single combat, before he is accepted." "And if he fails?" Torcred's eyes were fixed ahead, where a pale light was reflected by the ground that was flat now and gleamed whitely, encrusted with salt. "And if he--or she--fails," the girl's voice dropped low, "it is the last time." A sob came into her voice. "Even if I could go back to my people, I would be degraded to menial labor or breeding--could never fly again." Torcred felt pity for her despite his prejudices; and at the same time her words recalled his own worries, and he frowned blackly. The girl mistook his expression for an indication that she had somehow said too much, and she sank back into brooding silence. She glanced up only when the car's wheels ground to a stop on the salty crust, and Torcred, with a relaxing sigh, was already unsnapping his safety belt and switching off the panting motor. The girl saw flames and shadows amid which black figures moved, and she shrank back in fright, uncomprehending. As the Terrapin flung open his door, mingled sound of clanging metal and hissing fire rushed in to increase her confusion. He paused momentarily; his expression was unreadable as he gazed on her white face. "Stay where you are and make no noise," his low voice rasped sternly. "I'll come back."