"You're insane!" snapped Allison. "I just landed on this planet! You saw me land! I don't know what happened before I got here! How could I?" "You might have arranged it," said Calhoun. * * * * * Allison assumed an air of offended and superior dignity. Calhoun drove the car onward at very much less than the head-long pace he'd been keeping to. Presently he looked down at his hands on the steering wheel. Now and then the tendons to his fingers seemed to twitch. At rhythmic intervals, the skin crawled on the back of his hands. He glanced at Allison. Allison's hands were tightly clenched. "There's a ground-induction fence in action, all right," said Calhoun calmly. "You notice? It's a cattle fence and we're running into it. If we were cattle, now, we'd turn around and move away." "I don't know what you're talking about!" said Allison. But his hands stayed clenched. Calhoun slowed the car still more. He began to feel, all over his body, that every muscle tended to twitch at the same time. It was a horrible sensation. His heart muscles tended to contract too, simultaneously with the rest, but one's heart has its own beat rate. Sometimes the normal beat coincided with the twitch. Then his heart pounded violently--so violently that it was painful. But equally often the imposed contraction of the heart muscles came just after a normal contraction, and then it stayed tightly knotted for half a second. It missed a beat, and the feeling was agony. No animal would have pressed forward in the face of such sensations. It would have turned back long ago. No animal. Not even Man. Calhoun stopped the car. He looked at Murgatroyd. Murgatroyd was completely himself. He looked inquiringly at Calhoun. Calhoun nodded to him, but he spoke--with some difficulty--to Allison. "We'll see--if this thing--builds up. You know that it's the Texia--trick. A ground-induction unit set up--here. It drove people--like cattle. Now we've--run into it.--It's holding people--like cattle." He panted. His chest muscles contracted with the rest, so that his breathing was interfered with. But Murgatroyd, who'd been made uneasy and uncomfortable before Calhoun noticed anything wrong, was now bright and frisky. Medication had desensitized his muscles to outside stimuli. He would be able to take a considerable electric shock without responding to it. But he could be killed by one that was strong enough.