"And just how," I said savagely, "did that peanut brain of yours plan on your getting out of here without him?" Baxter paused, his gun hand wavering. "Because if he melts in the river, or is vaporized right here and now, you will be stuck without a light. Stuck in a rock-hard maze that you couldn't negotiate alone if you had a light." Baxter just stared, thinking furiously. "Of course," I went on, "you could simply aim that thing upward, and disintegrate your way out. But that, too, might make the ceiling fall in. And if it didn't, you'd have the small difficulty of climbing the glass-sided well you'd created. Climbing, by the way, into the Martian desert, where there is no air, no water, and very little heat. You'd be dessicated, suffocated, and a popsicle to boot!" "I--I could very easily slant the bolt into Marsport," Baxter blustered. "I could climb the slope easily enough, and there'd be fresh air waiting for me, too." "Yeah," I mocked, folding my arms. "Fresh air and a city full of insurgent Baxter-haters. Assuming, of course, that you didn't strike an underground stream in the process, and get washed away into the depths of the planet when your hold-off stance with the collapser tired you out, when you'd completely dissipated the charge." "I--" Baxter said, desperately nervous. "And also assuming," I continued, "that you know in which direction Marsport is, chum! Of course, you could swing that thing in a full circle of slant-blasts toward the surface, but then that would make the ceiling fall in, wouldn't it, once you'd cut away all supports." Baxter trembled with impotent rage, but his gun's muzzle was finally slumped all the way toward the floor of the tunnel. He was beaten, and he knew it. And that's when I jumped him. My still-working right arm shot down and gripped his right wrist, a very awkward stance to take, but my left arm was still weak and useless from my fall. But Clatclit moved in, then, his rocky talons sinking like so many fangs into Baxter's right arm, all three of us a writhing tangle on the tunnel floor, each of us frantically aware that the gun had better not emit any bolts while an arm, leg or tail flailed in front of it. Baxter shrieked with fear and rage as those steely fingers took hold. I think he was too upset otherwise to feel the pain. And then a bolt buzzed blindingly into the tunnel, and as we all three flattened ourselves and waited for the ceiling to come crashing down, it spattered into nothingness against the wall. We sat up, staring at the spot where the so-called invincible bolt had simply been dissipated, all of us looking pretty silly, flat on our bottoms, leaning back on our hands on that curved stone surface, momentarily losing sight of our belligerent behavior of a moment before. "The wall!" I said, first to realize the significance. But I couldn't go on. Baxter finished for me. "It's parabolite!" he cried.