Birrel felt the imminence of onrushing danger. Danger, not just to himself, but to all his world. For in him lay the only chance to find out about the threat to Earth before it materialized. Who their pursuers were, who the Irrians and Vannevan might be, and why they had come to Earth, he could not guess. But about Kara and Holmer, he was sure. Their colleague, the dead Rett, had had those pictures of Earth's most secret weapons and defenses on him. They, therefore, were the danger--and he must not lose them. "Turn at the next side road!" he said to Holmer. "We can give them the slip in the back roads." Holmer nodded. Birrel looked back. A pair of headlights swung steadily along a quarter-mile behind them. "They're closer," said Kara. Birrel looked ahead, saw the sign that marked a crossroad, and said, "Turn there!" Next moment, he thought they were all three done for. For Holmer turned into the dark side road without slowing down at all, and the sedan careened on screaming tires and threatened to go over. Birrel, slammed into a corner of the back seat, felt Kara bump against him. He held her with one arm and groped frantically for something to hold onto when they rolled over. They didn't roll over. By scared reaction, Holmer spun the wheel at the right second. The sedan tottered, then thumped back onto all four wheels, its motor stalled. Out on the main highway, a car flashed by fast. "These cursed Earth vehicles!" said Holmer, in a shaky voice. "No gyroscopic controls, no built-in stability factor at all!" Birrel felt like yelling, "What the devil made you think you could turn a right angle at full speed?" But he didn't. It would give him away, as Rett he mustn't know too much more about automobiles than the others did. But for the sake of survival he had to get Holmer away from the wheel. He said, "Let me drive it--since I saw you last I've learned to handle them pretty well." Holmer crowded over in the front seat, holding the black box in his lap. Birrel climbed over fast, and took the wheel. "They went past, but now they're coming back!" cried Kara. "I can hear--" Birrel kicked the starter and then the gas-pedal, and the sedan shot up the dark asphalt country road like a frightened rabbit. Kara was looking back, and her voice came clear over the rising whine of the motor. "They're back there. Gaining on us--" Birrel glanced up at the mirror and the headlights coming up fast behind. He jammed the gas-pedal down, sending the sedan hurtling past the lighted windows of houses, the black masses of trees. The headlights came no closer. Kara cried to Holmer, "Use the--" Again, the word that Birrel did not know. He knew what it meant. The square box in Holmer's lap, the thing that had stricken all in the prison unconscious by its potent vibrations. Holmer fiddled with the box. Over the roar of the motor, Birrel could not hear it come on. But he looked up hopefully at the mirror. The headlights stayed right with them.