“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.