Caliban made no reply. He brought the aircar up to hover power, taxied it out from under the camouflaged roof of the hangar, and kept moving forward until they were over the lake itself, the hover effect throwing up a shimmering mist of water that enveloped the car. Caliban lifted the car just enough higher so as to get above the hover mist, and look about at the landscape that was about to die. In a few minutes, all of this would be erased for all time. He and Simcor Beddle would be the last beings ever to look upon it.

Caliban lingered a moment longer, and moved the throttle forward, pointing the nose of the aircar up and to the east.

The east, thought Caliban as he guided the aircar toward the hope of safety. East. Home of the dawn, and new beginnings. He wondered if he would live long enough to see another sunrise.

“ALL FRAGMENTS ON course,” Unit Dum announced. “All fragments are descending well within their intended parameters. The operation is proceeding according to plan. Impact of the first fragment in five minutes, twenty-two seconds.”

Fredda Leving felt her heart pounding, her mouth going dry. They were going to do it. They were actually going to do it. This mad idea had moved from improbable theory to undeniable fact. They were about to drop a comet on their own world. She found herself amazed by the boldness, the courage, the desperate willingness to try something-anything-in order to save the planet. It was not the sort of action the universe expected out of the Spacers. It was not the sort of thing Spacers would ever do.

And it suddenly occurred to Fredda that perhaps they were not Spacers anymore. The world of Inferno was about to change beyond recognition. Perhaps the people of that world were going to change as well.

And that thought inspired a most un-Spacerlike reaction in Fredda. Spacers were supposed to be cautious, conservative, and frightened of change. But the thought of change did not scare Fredda. It excited her. She was impatient for it. She glanced at the countdown clock and decided she wanted the next five minutes and ten seconds to pass as quickly as possible.

She couldn’t wait for the future to get there.

DOWN THEY CAME. streaking in toward the planet at impossible speed. Twelve of them, moving in unison, in concert, like beads on a string, spread out on a north-south line, moving through the dark and the silence and their destiny.

The first fragment reached the upper limit of the atmosphere, and suddenly the time for dark and silence was over. The comet fragment struck the upper air at close to double orbital velocity, and all at once the forward surface of the fragment was aglow with the fires of immolation. Down thundered the massive piece of sky, a blazing torch that tore a hole in the atmosphere, smashing a column of superheated air out of its way as it hurtled toward the ground.

At the speeds the fragment was traveling, it took all of ten seconds for it to traverse the atmosphere. But before it could strike the ground, the second fragment slammed into the atmosphere, ramming through the massive shock wave produced by the first. The second fragment screamed groundward at a slightly more oblique angle, and thus had further to move through thicker air. The first fragment struck the ground just as the second was midway through its atmospheric transit, and just as the third was striking upper air.

Atmospheric contact had induced a massive energy release of light and heat, but the violence of hard-surface impact made what had come before seem utterly trivial by comparison. The first fragment slammed into the ground with incredible force, smashing the surface out of existence as it blasted apart into a million, a billion pieces, shards of rock and ice and steam dust roaring outward at supersonic velocity.

The second fragment struck with equal destructiveness, and the third, and the fourth, one after another, twelve massive hammers wielded by some forgotten god of war. It was a rain of stone and ice and fire that marched steadily north across Terra Grande from the shores of the Southern Ocean to the borderlands of the Polar Depression.

The last fragment smashed into the southernmost edge of Inferno’s inconsequential northern icecap, and suddenly the polar sky was a thunderclap of steam and smoke and fire, ice that did not have time to melt before it flashed away into superheated steam. Sea water thrown up by the first impact on the shores of the Southern Ocean splashed down onto the steaming maelstrom of the Polar Depression, even as shards of icecap that had survived the initial impact dropped into the depths of the Southern Ocean. Water from the south reached the north, and vice versa. As a dozen massive new craters glowed in angry red, belching fire into the sky, touching off fires and wreaking havoc on the land, the new water circulation pattern had already begun.

The fires blazed as brightly as any in the Hell that had given this world its name. But some fires light the way to hope, and for the planet of Inferno, the future had finally begun.

“WHY?” ASKED SIMCOR Beddle, and Caliban did not have to ask him to explain the question. He knew what the man wanted to know.

The aircar moved through space, traveling in a synchronous orbit of the planet. Down below, twelve angry red wounds on the planet were beginning to cool, their color fading away. Neither man nor robot could tear his eyes away from the incredible and terrifying sight.

“I did not save you for your own sake,” said Caliban. “Nor simply because you are a human. I came after you for the reasons I explained in front of Prospero. Sooner or later, others would have deduced what I deduced: that a mad New Law robot had found a loophole in the New Laws, and invented a way to kill humans. There would not have been a New Law robot left alive thirty hours later, and I expect there would have been attempts on my life as well. The news of what Prospero attempted will still get out, of course-but you are not dead, while the mad robot in question is.”

“But there was that moment,” Beddle protested. “I admit that I was not thinking clearly at the time, but there was that moment when Prospero suddenly presented the situation as a choice between the two of us, between Prospero and myself. You chose me. Why? Why did you choose a human enemy over a robot friend? You could have killed me without any risk of legal detection. Why didn’t you?”

“It was clear that I could not bring both of you out alive. I did not wish to kill you both. I am no butcher. I had to choose. But there was not much to choose between the two of you,” Caliban said. “I don’t believe that Prospero actually could have survived if you had died through his actions, in any event. Even the New First Law would have imposed fatal stress. It was a severe strain for him to believe that he was not violating the New First Law. If he had actually accomplished his goal, I believe the strain would have been too much. He would have gone utterly mad and died. But that was almost incidental. You are quite right. When Prospero framed it as a choice between the two of you, I had to have some basis for choosing, some criterion. And then I thought of the robots, Three-Law and New Law, that Prospero had killed for no greater crime than simply getting in his way. That is what decided me.”

“I see,” said Beddle. He hesitated for a moment. “I am about to speak with more frankness than wisdom, I suppose, but be that as it may. I have to understand this. It has to make sense to me now, today. Otherwise some part of me will spend the rest of time wondering why Caliban, the No Law robot, didn’t kill me when he had the chance. Surely you must know that I have destroyed robots many times, whenever it suited my convenience. So what difference is there?”