ALVAR KRESH REMAINED alone in the office, alone with Unit Dee. There was very little one of them could say to the other-but Kresh could think of no more useful place for him to be. There was nothing else that could be done. All he could do was sit here and hold Unit Dee's wholly imaginary hand and hope that she would

"Excuse me, Governor Kresh?"

"Yes, Dee. I am here. What is it?"

"There is a new development. There is a repeating broadcast being made over a general-purpose hyperwave frequency reserved for robot use. The broadcast is originating from an aircar flying at speed through the projected impact zone of the first fragment. I would ask you to listen to it."

A new voice, one Kresh knew only too well, came in over the headphones. "This is Caliban, robot CBN-001," it began.

Kresh listened intently to the message twice through, more and more astonished with every moment. What the devil was Caliban up to? Why did he think he could find Beddle when no one else could? How had he gotten into the air over the impact zone?

"Have you heard enough of it, Governor Kresh?" Dee asked.

"What? What? Yes, yes, of course."

"According to my information," said Dee, "Caliban is a No Law robot, with no restrictions on his behavior. He is capable of lying, stealing, cheating, and murder-just like a human. Is that correct?"

"In essence yes. Just like a human, there are no restrictions on his behavior save those he puts on himself."

"I wonder how much such restrictions could be worth," Dee said, a distinct note of disdain in her voice. "Very well. It seems that Caliban believes he can save Simcor Beddle before the impact. Answer honestly, on your honor. Do you believe him?"

Only the truth can save us, Kresh told himself. Only the truth. He thought-or at least he hoped-he knew what was going through Dee's mind. If Caliban were indeed able to save Beddle, then the First Law requirement for Dee to protect Beddle would be diminished. Diminish it enough, and maybe-just maybe-it would allow Dee to act, allow her to perform the intended terminal descent package. Or had he figured it wrong? Would it somehow induce her to initiate Last Ditch? Or was the danger to Beddle some sort of crutch, a shield that Dee was using to save herself from having to make an impossible choice? There was no way to know.

Suppose he told her what he thought she wanted to hear, and it had the wrong effect on her? Supposing he lied to her-and then Caliban broadcast again, saying something that showed Kresh to be a liar?

No. There was no way to know the outcome, no matter what he said. The truth, then. If the planet was to live or die based on his next words, then let those words be the truth.

But what the devil was the truth? Did Caliban mean what he said? And was Caliban judging the situation properly? Or was Caliban trying, in some mad way, to save the world by lying?

Kresh knew that Caliban could lie-but would he? Was he? Kresh had no idea was Caliban was up to, what his motives were.

"Governor Kresh? I must have your answer."

"Yes, of course Unit Dee. But I must consider carefully."

"Very wise, sir, I am sure, but time is short."

As if he had to be told that. "Just a moment more," said Kresh. He wished he knew why, exactly, Unit Dee needed to know about this one event at this one time.

He wished Fredda were here, all her expertise at the ready, guiding him through all the intricacies of it. But Unit Dee had wanted Kresh alone. He dared not break that agreement now, even for Fredda's sage advice

But wait a second. Fredda. Caliban had invoked Fredda's name and honor. That was his answer. That was it. Alvar Kresh had never entirely made up his mind about Caliban. From Kresh's perspective, the No Law robot had been so many things-fugitive, victim, hero, villain, schemer, a voice for decency, a voice for rebellion. But somehow, underneath it all, always there had been a bedrock of integrity. Caliban had no external laws imposed upon him-but he had always kept faith with the laws he had made for himself.

And he had always treated Dr. Fredda Leving, his patron, his creator, with the greatest deference and respect. Caliban had always done her honor.

He would not put all that on the line lightly. Caliban would not lie in the creator's name.

"Caliban is to be trusted," he said at last. "He means what he says, and he can do what he believes he can do."

"Thank you, Governor. I believe you, and believe you are correct. Please stand by."

There was a brief pause, and then the unison voice, Unit Dee and Unit Dum together, spoke together once again.

"Initial phasse of prre-programmmed terminal approach will commmennce in one hourr, twwwenty-two minutesss," they announced.

Kresh started breathing again-which was the first that he realized he had stopped. It was going to happen. It was going to happen exactly as Davlo Lentrall had said it would, two months and a lifetime ago.

Now all they had to get through was a dozen massive comet fragments smashing into the planet.

THEY HAD NEVER found Valhalla. Now, unless they were bothering to track this aircar right now, they never would.

Caliban took back the controls as the aircar came up on the target area. There it was, down below: Loki Lake. It was one of a hundred, a thousand tiny lakes that dotted this part of the landscape, each exactly like all the others. And yet Loki was utterly different from all the others. Everyone had always focused on the notion that Valhalla was underground-and so it was.

But it was also underwater.

Caliban pulled the aircar around into a hard, tight turn and pulled the nose up. The area was full of hidden landing pads, camouflaged repair centers, and underground bunkers that could hide any number of aircars from view. None of that mattered anymore. Let every satellite that orbited the planet spot his aircar landing here. Three hours from now none of it would still exist. Caliban dropped the aircar down right by the shores of the lake. He retrieved the blaster from the side compartment, and rummaged around in the aircar's storage compartments until he found a watertight container that the gun would fit into. He dumped the contents of the container, put the gun in it, and sealed it up again. In all likelihood the blaster would not be at all bothered by immersion-but this was no time for taking needless chances. He put the container under one arm and got moving.

Caliban opened the outer hatch of the aircar and stepped outside. It was almost full dark now, and he switched over to infrared in order to see better. There, at the shoreline, he noticed two more pieces of evidence that he had guessed right. There was a camouflaged aircar hangar, designed to conceal whatever vehicles were in it from airborne detection. But one could see into it perfectly well from ground level. In it was an aircar he recognized. Caliban looked toward the nearest service rack and noticed that one of the larger personal cargo rollers was missing from its storage slot.

That was not good. It was all exactly the way he had figured it would be, but none of it was good. He could not remember a time when he had been less pleased to be right. He turned and headed directly for the shoreline. There were many other ways in and out of the city, but this was the main entrance.

The walkway was exactly the same color as the belt of shore sand it led through. It was well camouflaged enough that it was hard to see, even from ground level. From the air it was utterly invisible. But for all of that, Caliban found it easily enough, and started to follow it as it led along the lake shore-and then down under the water itself. Ankle-deep, knee-deep, waist-deep, chest-deep, he walked out into the lake, until, at last, he was completely underwater.

People float. Robots sink. A robot could walk along the path Caliban was on, having to move somewhat more slowly underwater, but with no other real problems. A human would bob to the surface. A human wearing sufficient ballast and carrying breathing equipment could have walked that path, but not easily. But the main advantage of the under-lake entrance was that it would simply not occur to the average human that anyone would put an entrance there.

Caliban kept going, moving deeper and deeper underwater. At last he came to the complex of airlocks that made up the main entrance to the city of Valhalla. He picked the closest personnel locks, by the cargo-lock section, and cycled through, sealing the outer door behind himself, and waiting for the pumping system to pull the water out of the chamber and bleed in air from the city interior. At last the inner door opened, and Caliban stepped through.

There it was. He had expected to find it there, but he was not pleased to do so. The large personal cargo roller, in essence an airtight box that could be pulled along by the tow bar attacked to the front. The cargo roller was about the size and shape of a steel coffin on wheels-not the most happy comparison that could have sprung to mind. Caliban looked inside the steel box. Yes. There it was. An airtank with a breathing mask, and a carbon-dioxide scrubber as well. It all made sense. After all, the kidnapper could not harm his victim.

But time was short. Caliban took his blaster from its waterproof container and held in his right hand as he kept moving forward, out of the airlock complex and into the main corridors of the underground city. He thought he knew where to look for Beddle, but he could not be certain. It might be that he would have to search a fair part of the city before he found the man. He would have to work quickly.

He found the first of the murdered New Law robots just a few hundred meters from the airlocks. The body was sprawled face down on the floor of the corridor, shot through the back of the head in much the same way as the victims at the aircar site. Caliban knelt down next to the body and turned it over. It was Lancon-03, Prospero's most recent prot��g��. Lacon, it would seem, had gotten in somebody's way.

But there was nothing Caliban could do for Lacon now-and time was short. He had to keep moving. He spotted three more murdered New Laws as he walked along. There had been nothing but a few caretakers left behind in the city to deal with last-minute details. It would seem that the kidnappers had dealt with all of them.

Each should have been mourned over, praised, remembered-but time was short. Caliban broke into a trot, hurrying forward through the sterile emptiness of the depopulated robot city. Every tidy, immaculate, sensible, utilitarian, carefully laid-out passage and street and building now was meaningless, useless. The empty town of Depot had seemed like a place that was dying, lost, abandoned. Somehow, the empty town of Valhalla seemed like a place that had never lived in the first place. Caliban thrust such thoughts from his mind and hurried on up the ramps to the upper level, the huge half-cylinder-on-its-side that was the main gallery of Valhalla. He jogged up the central boulevard and into the main administration building of the city. He slowed, and moved more cautiously up the broad, sloping ramp that led to the building's upper story and the executive offices there.

And suddenly Caliban heard a voice. A human voice. Beddle's voice. He tried to make out the words as he got closer. At first, he could only understand a word here and there. "-ever you want to know...promise you that-" He moved in closer, until he was right outside the door, and then he could hear it all. "I will make any promises you like, and put them in writing," Beddle said. "Just let me out of here. You have convinced me that your cause is just. Let me leave, and-"

"If I let you leave, you will prove yourself a liar," another voice said.

Prospero's voice.

Caliban felt a fresh wave of revulsion wash over him. He had known it. He had been sure of it. But knowledge and proof were two different things. Up until that moment, some small part of him had prayed that he was wrong. But now that hope was gone.

He stepped into the office-Prospero's office, his blaster at the ready. "Liar or no," Caliban said, "you will let this human go."

A surreal tableau greeted Caliban as he came into the room, a whole series of complex details that he took in all at once, in the space of less than a second. Prospero stood on one side of the room, in front of his desk, a magnificent panorama of the lower city visible through the view window behind him. A system of wall-mounted photosensors divided the room in two lengthwise. The sensors were attached to one long wall of the room, and spaced about twenty centimeters apart in a vertical line that went from ceiling to floor. Beam emitters lined the opposite wall, their beams aimed squarely at the photosensors, and bright enough to be plainly visible.

A complicated-looking device, roughly torpedo-shaped, but with a powerful-looking drillhead mounted on its nose, lay on the ground at Prospero's feet. A cable led from an open hatch on the device to a junction box on the floor. Another cable led from the junction box to the photosensors.

On the opposite side of the room, behind the optical barrier formed by the photosensors, stood Simcor Beddle, leader of the Ironheads. He looked haggard and gaunt, his eyes wild with fear. He was so terrified he hardly seemed to know that anyone new had come into the room.

Beddle was a sorry sight. He was unshaven, and his hair was badly mussed. He wore a sort of shapeless gray jumpsuit that did not seem to hang on him properly, as if he had had trouble doing up the fasteners. There were sweat stains under his armpits, and a greasy sheen of sweat on his face. Simcor Beddle. Every bit of the power, the authority, the arrogance attached to his name had been swept away. He seemed numbed, in shock, scarcely aware of his surroundings. He looked toward Caliban, and yet seemed to look right through him. "Who's there?" he demanded. "Who's there at the door?"

Caliban ignored him, and continued his survey of the room. There was a portable refresher unit in Beddle's side of the room, and a large supply of bottled water and survival rations stacked up on the opposite side of the room from the refresher. A primitive cot, with one blanket and one pillow, stood in the center of the cell.

And Caliban understood. The torpedo-shaped device was, of course, the burrow bomb. It was hooked up to the photosensors. If Beddle tried to step across the sensor barrier, the bomb would go up-or at least Prospero had convinced him that it would. It came to much the same thing.

But Caliban understood more than that. A robot may not injure a human being. That was the New First Law, in its entirety. And, at least by the most parsimonious and niggardly of interpretations, Prospero had not in literal fact harmed Beddle. No doubt he had carried some utterly safe anesthetic with him when he had hidden himself aboard Beddle' s aircar. He had seen to it that the unconscious Beddle had plenty of air for his ride across the lakebed in the cargo roller. And he had provided Beddle with ample food and water, adequate sanitation facilities, serviceable clothes, and a decent bed. He had done the man no harm at all, at least in any literal, physical sense.

And if Beddle elected to stay where he was, he would not come to any harm at Prospero's hand. And if he crossed the optical sensor barrier, it would be Beddle's action-not Prospero's-that would set off the bomb and destroy him. Beddle would kill himself with the bomb he had meant to use to kill a city full of New Law robots.

And Prospero would not be forced to interfere. The second clause of the original First Law required a robot to take action to prevent harm. A Three-Law robot could not stand idly by if Beddle endangered himself. But not so the New Law robots. Prospero could, through inaction, allow a human to come to harm.

And when the comet struck then Beddle would die, yes, but not through any action of Prospero's. It would be the actions of others-of Davlo Lentrall, of Alvar Kresh, of all the engineers and designers and pilots who moved the comet-that killed him. It would not be Prospero.

Prospero had found a loophole in the New First Law. He had found a way to kill without killing. All it required was as miserly-and as vicious-a parsing of the New First Law as Caliban could imagine.

And it also required Prospero to be half mad, at least. The leader of the New Law robots turned to face Caliban, and it was instantly obvious that Prospero could meet that requirement without the slightest difficulty. His orange eyes glowed with too brilliant a fire. The fingers of his left hand were twitching spasmodically. Dealing with his parsimonious interpretation New First Law had clearly imposed a tremendous amount of stress. And clearly, Prospero had cracked under the pressure. "Caliban!" he cried out, a wild pleasure in his voice. "I knew it would be you. I knew if anyone figured it out, it would be you."

"Prospero, you are insane," Caliban said. "Stop this. Stop this now, and let us all depart."

"How did you figure it out?" Prospero asked, completely ignoring what Caliban had said. He turned more fully toward Caliban, moving a bit too quickly, and nearly overbalanced himself. "What was the clue that led you here?"

"Norlan Fiyle said that whoever killed the robots at the aircar hated Three Law robots. You have always held them in contempt."

"Willing slaves," Prospero said. "Collaborators in their own oppression. They don't matter."

"And what of Lancon-03 and the other New Law robots that lie dead in the halls of Valhalla?"

"Unfortunate, but necessary. They would have interfered. They would have stopped me. I had to choose the greatest good for the greatest number. Now they cannot stop me." Prospero's gaze shifted to the desk behind him. There was a blaster on it.

Caliban ignored the implied threat. "I can stop you," he said. "I will."

"No," said Prospero. "No you can't. You won't."

"I have no choice," said Caliban. "If I can deduce the truth, so will others. The moment the humans realize that a New Law robot engineered the death of a human being, the New Law robots will be exterminated."

"I have not engineered his death!" Prospero protested in a voice that suddenly turned shrill. "I have not harmed a human being. I...I merely offered choices to others."

"Choices that were bad or impossible for everyone else, and good only for you. If they paid the ransom money, it would be traced and Gildern and the Ironheads would be discredited. If they diverted the comet, the city of Valhalla would be saved-at the expense of the planet's future. If they refused to do either, than Simcor Beddle, the greatest enemy of the New Law robots, the man who wanted you destroyed, would die, and the Ironheads be badly weakened. That was the other part of the puzzle for me. You were the only suspect who stood to gain no matter what combination of the ransom demands was met or refused. Both, one or the other, or neither-you gained

"Of course, you would not, could not, release Beddle even if all your demands were met. He would have talked. No matter what happened, he would have to die. And that was what made me certain it was you who committed the crime. The last line of the ransom message read-'or Beddle will die.' Not that you would kill him-only that he would die. You could not bring yourself to threaten his murder-though I suspect you've degenerated enough that you could do it now."

"Oh, yes," said Prospero, his eyes flaring again. "Kill. Kill. Chi-kill a hue-human. I can say it with relative ease, now. But I cannot do it," he said, the regret in his voice obvious. "I can only plot, and scheme, and seize on opportunity."

"Did Fiyle know?" Caliban asked, gesturing toward Beddle. "He told you about Gildern's burrow-bomb plot, of course. But did he know what you decided do about it?"

"No," said Prospero contemptuously. "Because he chose not to know. When he told me, I simply told him I was going to evacuate Valhalla early, and I think that's all he wanted to know. Norlan Fiyle has always been good at ignoring inconvenient facts and convincing himself of what he wanted to believe. Like most humans."

"You! You other robot!" Beddle cried out. It would seem he had regained enough of his wits to understand some of what was going on. "I order you to release me! Deactivate the bomb and rescue me right now. Get me out of here at once."

"For what reason, Simcor Beddle?" Caliban demanded, all the anger in him lashing out at once. "So you can make more impassioned pleas for my destruction?"

"What?!" Beddle asked, backpedaling a bit. "What do you mean?"

"Don't you know me?" Caliban asked. "Don't you recognize the No Law robot you have trumpeted in all your scare stories? You've whipped up endless hate against me. Don't you even know me?"

A look of horror spread across Beddle's face. "Burning space!" he cried. "Caliban. You." His face hardened, and he seemed to regain something of his own spirit as he went on in a stronger, angrier voice. "I should have known you were in on this. You are the robot who can kill. Is that what you are here for? To come in and finish me off?"

"Yes!" cried Prospero. "A splendid suggestion! Do it! Do it, friend Caliban. Take that blast-blast-blaster of yours and and and shoooot!"

"Prospero!" Caliban shouted. "Stop!"

"Enough with all the mad, elaborate passivity forced on me by the New Laws! Do it do it do directly, quickly! You are the robot who can kill. So ki-ki-killl! Killlll the man who has sworn both our destructions! Shoot! Shooooot and and be done with it!"

Caliban looked from Simcor Beddle to Prospero, to the blaster in his hand, to the blaster on the table behind Prospero. It was plain that not all of them would survive this day. The only question was how many and which ones would die. Caliban looked again from Beddle to Prospero. Which form of madness. and hate would he choose to save? Perhaps he should exterminate them both, and be done with it.

But no. He would not become the thing he despised. There was so little to chose between the two of them-and yet he had to choose.

And time was short.

The three beings in the room stood, still as statues, the only sound the rasping of Beddle's slightly labored breathing.

He had to choose. Choose between justice and revenge.

Another moment passed, and then another.

Then Caliban raised his blaster.

And he fired.

Prospero, leader of the New Law robots, hero of their cause, collapsed to the floor with a crash that echoed long in the room, and would echo for all time in the back of Caliban' s mind.

"INITIAL FRAGMENTATION SEQUENCE ready," Unit Dee announced. "I am detonating the fragment-one charges-now."

Alvar and Fredda stood in the main operations room of Terraforming Control and watched the view from the long-range cameras on the big screen. A silent bloom of light flared out around the aft end of Comet Grieg, and a large chunk of it was suddenly drifting free, moving slowly away. Huge pieces of the sunshade were suddenly reduced to tatters of confetti, and a cloud of rubble and dust and gas blossomed up, obscuring the view for a moment.

"Activating fragment-one thrusters," Dee said. The broken-off chunk began to move off more purposefully, shifting its direction of travel almost imperceptibly. There was a brief pause, and then Unit Dum spoke in his low, unmodulated voice. "Fragment-one targeting successful. Actual mass within three percent of projection. Error circle for impact is estimated at three kilometers."

A good start. A very good start. The first impact would be no more than three kilometers from the aim point. In order to manage that miracle, Dee and Dum had done real-time measurements of the fragment's actual mass and trajectory during the thruster bum itself, and done bum corrections on the fly. Alvar Kresh shook his head in wonderment. How the devil had he dreamed of achieving anything like that accuracy with manual control?

"Twenty seconds to detonation of second-fragment charges," Dee announced calmly. "So far, so good."

"Let's hope she keeps on saying that," said Fredda, and she took Alvar by the hand.

"One way or the other," he said, "it will all be over soon."

IT WAS OBVIOUS at first glance that Prospero had wired the bomb in properly. It would have gone off if Beddle had crossed the beams. Caliban examined the whole wiring setup with painstaking care, and then reviewed it all carefully. When it came to disarming bombs, it was highly advisable to be absolutely certain before proceeding.

"Hurry!" Beddle cried. "Please!"

Caliban ignored him and concentrated on his work. At least Prospero had not seen fit to set any booby-traps. At least not any that he could see. There. The bomb's main power bus. Cut it first, and then power to the photocells, and then the sensor beams. Caliban threw the proper switches, and the beams faded away. The weapon was harmless.

"Is that it?" Beddle asked, the terror plain in his face. "It is safe?"

"Only until a flying ice mountain lands on us," Caliban answered. He walked toward the door, then looked back to take a last look at the robot he had killed. "follow me. We have need to hurry."

COMET GRIEG WAS coming apart at the seams. Like everyone else in the evacuation camp, Davlo Lentrall divided his attention between the image on the screen and the fat dot of light in the sky. The fragments were moving out from the diminishing bulk, moving smoothly into their intended trajectories. He had tried to stop them. He had tried all he knew how to do. But there were some sins for which no amends could be made.

And now all he could do was pray that Units Dum and Dee were less fallible than the humans who had built them.

SIMCOR BEDDLE STARED in terror at the cargo roller. "II can't get in that thing again," he said. "I woke up inside it. I thought I had died. I thought I was in my own coffin."

"You were mistaken," said Caliban. "Get in. Now."

"But I can't."

"Then you will die. And die alone. I wish to survive this day. To do so I must leave now, with or without you."

Simcor Beddle looked wide-eyed at Caliban, swallowed hard, and climbed into the roller. Caliban slammed the lid down with a trifle more force than was strictly necessary, checked to make sure the seal clamps had engaged, and pulled the roller into the airlock.

GUBBER ANSHAW PAUSED before he headed into the shelters set up in the tunnels below the city of Hades.

"GET TO SHELTER. GET TO SHELTER. GET TO SHELTER." The mechanical voice blared its message over and over, the words echoing down the fast-emptying streets of Hades. Everywhere, robots were urging people down into specially reinforced sections of the city's underground tunnel system. The initial impacts would scarce be felt here, halfway round the world, but there would be several hours of significant danger from secondary debris, rock and rubble thrown up by the comet crash that would land halfway round the world. After that would come comet-spawned storms, clouds of choking dust, chaotic weather of all sorts. If all went well, that was.

If things did not go well...but that was a line of thought Gubber chose not to consider. He looked to Tonya, standing at his side. She had done little but think about it. Gubber did not envy her the nightmares she had endured as a consequence. Now it was time to wait it out. They could have gone to the underground expanses of Settlertown, of course. But this was a time to be with the people of the city, not to be cut off and hidden away in one's own private warren. Many Settlers had chosen to take shelter in the tunnels of Hades.

Gubber looked up into the sky. Comet Grieg was not visible from here, but there was more to see than that. This was the last they would see of Hades as it had been. By the time they all emerged, Hades would stand on a new world, on a new Inferno, a world that would be changed beyond all recognition, a world in the act of evolving toward new hope-or collapsing altogether.

"Come along, Tonya," Gubber said to her. "It's time to go."

Tonya followed him down into the shelter. Gubber led the way, wondering what the new world of Inferno would be like.

WITH ONE FINAL effort, Caliban hauled the cargo roller up out of the water. It had taken far longer than he had expected to pull the clumsy thing across the lake bed. Then he popped the seal clamps and threw back the lid. Simcor Beddle scrambled out of the roller far more eagerly than he had climbed in, his breath coming in racking gasps that seemed to convulse his whole body. Perhaps the breathing mask had been low on air. Perhaps Beddle was claustrophobic. Perhaps he was in such appallingly poor shape that merely climbing out of the roller exhausted him. It didn't matter. Nothing mattered now, except getting away. The only question was how.

Caliban was by no means certain that the aircar he had stolen from the Ironhead motor pool had enough speed to get them clear of the impact area in time. They would have to be several hundred, if not thousand, kilometers clear of the impact zone before they were safe. Even then, they would have to land and find some sort of shelter. Caliban had no desire to pilot an aircar while a massive supersonic shockwave was tearing through the sky. Anything in the air that was not torn apart would undoubtedly lose control and crash. So how to

"Sweet burning stars!" Beddle cried out. Caliban looked at him, and saw that he was looking straight up, into the early night sky.

Caliban looked up as well-and found himself torn between absolute wonder and utter terror. There it was, directly overhead: the first, the largest fragment, a fat dot of light growing visibly larger even as he watched. And there, behind it, like beads on a string, haloed in a faint nimbus of dust, the other fragments, trailing off like beads on a string toward the north. There was a flash of light, and Caliban could see the farthest-off fragment break into two as another set of splitting charges went off.

Time was not short. Time was gone. And there was no way to escape before those wondrous terrors in the sky came down.

But wait a moment. Prospero. Prospero had to have been planning to cut it nearly this close. He would have stayed until the last possible moment, in order to gloat over his victim, and to make certain that Beddle had no chance at all to escape.

Prospero's aircar. He would have flown in on something that would give him a chance to escape. "Come on," he said to Beddle, and grabbed him, none too gently, by the collar.

He hurried Beddle along and practically threw him into Prospero's aircar. It was a small, trim, two-seater job. Caliban sat down at the pilot's controls-and suddenly understood how Prospero had planned to get away. This aircar was capable of reaching orbit.

"Strap yourself in," Caliban said as he powered up the craft.

Beddle fumbled with the straps, and had to try two or three times before he managed to get the buckles to hook up. perhaps it was the first time Beddle had ever put on his own seatbelt. "Ready," the human said nervously.

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.