The Witch had clawed herself up into clear space, kilometers away from the highest lobes and tendrils of the invisible breakdown zone. Harry drew a deep breath, rejoicing in the sensation of freedom from all the strangeness that was Maracanda. He was back in a normal, honest world, with the prospect of starting what might be an honest fight, with weapons that could be expected to do their job. He had to call on all his skills, maximize his close relationship with the computers that made up the Witch's crafty and elegant brain. He had to determine at what speed and in which direction he wanted his ship to move. If the murderous berserker device had already been launched, it ought to be somewhere along an orbital curve between Maracanda and the pulsar Avalon.

Half a minute was enough to cure him of the illusion that he and his ship were free of strangeness. Stranger quirks of space-time than any his ship had traveled lay ahead, between the Witch and the swiftly moving neutron star.

Maracanda's automated system of robot guides and piloting advice, which generally guided local traffic, had shut down when the alert was called. But Harry's ship's data banks had incorporated an astrogational chart of the entire Maracanda system. That chart now began to blare stern warnings about the course he had just chosen, until Harry commanded the Witch to shut down the noise. He didn't doubt the close vicinity of Avalon was a dangerous place to be, but he wanted to get there as quickly as he could.

He and his ship engaged in a brisk and silent thoughtware dialogue, setting the ship on a course that would carry them quickly into the dangerous proximity of the pulsar. Contrary to what Harry would have expected in a normal system, almost continuous corrections were necessary.

Ever since the early stages of the alert, several Space Force ships, along with the Templars' single scout, had been deployed defensively around the habitable body, trying to keep themselves between its people and the expected onslaught from deep space. Harry now hastened to reestablish radio contact with those ships and with the ground facilities at Port City. The Witch had emerged from the maze at a spot where it had the broad expanse of the spaceport's cloud cover distantly in sight.

He also ordered an intensive search for any object in-system that could conceivably be a berserker vehicle recently launched from Maracanda.

In a few moments his ship's voice reported that nothing of the kind was visible.

"Keep trying!"

The communications gear had quickly become jammed with incoming messages, the holostage displaying the names and locations of half a dozen senders, all clamoring for a response. Before replying to anyone, Harry passed on an urgent warning to them all, based on what he had seen in the cave and heard from Dr. Kochi.

All of Harry's listeners rejoiced that he and his ship were back among them. As soon as they heard of the surprising rescue he had been able to accomplish, most offered congratulations. But the warning that the pulsar could soon be triggered into going hypernova was less readily accepted.

In a few moments Harry was deep in conversation with General Pike, cruising round Maracanda in a comparatively low orbit. Since shortly after his last talk with Harry, Pike had been hovering in space in his scoutship, more than half expecting that he and his small crew were soon going to die, opposing an overwhelming berserker attack that would come sweeping in from the system's outer reaches.

He and his scoutship crew, like their Space Force counterparts, kept looking outward, into deep space, for an attack that never came.

His first question was "Are my two men there? Teagarden and Zhong?"

"You can get a couple of medals ready, general, but they'll have to be posthumous. They met one real berserker on the ground."

Pike naturally wanted the details, but Harry insisted on first making sure his warning was understood.

Joining them on radio was Dr. Emil Kloskurb, now standing by in Templar headquarters in Port City. Hastily, Harry reported the circumstances of the hidden cave. Then he put Dr. Kochi on line. Speaking from the medirobot, she told her story, delivered her warning, and began to answer questions.

The general expressed suspicions about the way the alert had originally been called. "The first signal came from our distant early warning units, and yet the only place the enemy has actually been seen is on the ground. Does anyone have an explanation for that?"

(And Lily muttered, for her captain's ears alone: "Well, general, you have to remember that this is not a planet.")

All doubt that the alert was justified had vanished long ago; but it still seemed impossible to understand why, following that first ambiguous signal, no enemy machines had been detected in this system's space.

"We're standing guard, of course, and we'll do what we can. But anyone who tries to fight a space battle in the inner portions of this system is going to have the devil's own time doing it."

"How's that?" Harry demanded sharply.

"We run into the difficulty every time we try to conduct maneuvers. Space and time in-system here are never quite what you expect them to be, however much research you do - and not what your gunlaying system expects, either, whatever type you have. To put it simply, you are not likely to hit anything you aim at."

"Are you saying the berserkers won't be able to hit the pulsar when they drop their package?"

"Oh, I've little doubt that they could manage that. But their machine will have to get very close to its target, and there may be some lengthy maneuvering involved."

By now Dr. Kloskurb had spent several hours in Port City, convincing the local authorities that he generally knew what he was talking about. They were listening intently to the scientist as he admitted that he saw no reason why the threat reported by Dr. Kochi and Harry Silver could not be true.

"In calculating the gravitational interactions between Mara-canda and other bodies, you can treat it mathematically as if it were a sphere. But when you're working problems on the much smaller scale of ships and launch vehicles, of human bodies if it comes to that, things get much more complicated."

Kloskurb went on to say, "The devastation would go far beyond that caused by any ordinary nova, beyond what happens in the ordinary supernova types. It would reach hypernova status."

Someone else put in: "I thought that hypernovas were only a theory."

"They have been, until now. I don't claim cosmology's really my field, but - "

"Then let's talk to someone who does."

Experts in celestial mechanics were quickly located and brought into the discussion. When they had heard Dr. Kochi's report and warning, none of them were inclined to say that it was fantastic and should be disregarded.

One expressed the consensus: "In theory it would seem impossible to produce a more violent explosion, from any objects of equivalent mass."

No way had ever been found to send electromagnetic signals through flightspace to convey information any faster than solid vessels, ships, or robotic couriers could move in that exotic domain.

When natural disaster threatened on an interstellar scale, as in the case of Twinkler, humanity might enjoy the luxury of decades or even centuries in which to dodge destruction. Death by supernova could move to engulf its victims no faster than light itself. The strain on human time and resources would be enormous, and ragged fleets of refugee ships would provide good hunting for the berserker enemy, but still worlds and systems could be evacuated, whole populations resettled somewhere else. Not all life forms could be carried to safety, and in that the death machines could claim at least partial victory. Ultimately the berserkers' programming committed them to the destruction of all the lower forms of life, just as surely as to the obliteration of humanity.

"But that's not how they usually go about their job. They definitely assign priorities."

"They sure do. If they tend to concentrate their efforts on fighting us, it's because we're about the only life form in the Galaxy who can fight back. We keep interfering with what would otherwise be the neat and efficient pattern of their work. They must compute that once we're out of the way, the rest of the task should be clear sailing."

The most horrific possibility, which about half the assembled experts were ready to accept, was that an explosion of the type now threatened could actually propagate through flightspace. The evacuation time available, even for distant planets, would be reduced to only days, and the possibility of getting out a timely warning to them would be all but eliminated.

While the experts tried to digest the news and come up with a prediction, Harry and Lily were able to listen to reports, relayed through Port City, about the ground fighting still in progress in the east.

In the early stages of the alert, both Pike and Rovaki had successfully dispatched robot interstellar couriers from their respective facilities at the spaceport. The nearest bases of both Templars and Space Force, each only about a day away at c-plus velocities, were informed of the attack and asked for reinforcements. But several days must pass before any help could be expected.

Additional couriers were dispatched at intervals to carry news of the latest developments and updated estimates of enemy strength. The latest of those had been guardedly optimistic. It was even possible to predict an eventual human victory without reinforcement, given the small size of the enemy force and the fact that it included no large fighting machines.

There was no reason to doubt that berserkers could have devised a plan as intricate and cunning as that described by Dr.

Kochi. Some warped goodlife scientist might have been the originator, or the bad machines might have discovered it independently. Berserker computers were certainly capable of organizing and building complex engineering projects, and even engaging in scientific research, exercising their indefatigable patience. Their command units, like the greatest of human generals, were relentless in the pursuit of knowledge of any kind that would help them to destroy their opposition.

But history suggested that the champions of the cause of death, like other computer brains, tended to be no better than second-rate when engaged in pure research. They were all but incapable of truly insightful discoveries, unable to make the imaginative leaps that were so important in the thought processes of human investigators.

In every Maracandan settlement there were some who believed at first that the alert was only a false alarm. These scoffers were quickly converted when the machines showed up at the gates of Minersville.

The great majority of Galactic citizens had never laid eyes on a real berserker. The number of humans who had seen the real thing and lived to tell about it was astonishingly small. Even among combat veterans, very few had sighted the enemy except as red dots on a holostage. During those periods when people believed that the alert was genuine, they generally reacted in one of two ways. A majority of capable adults took up arms, while others ran screaming into the wilderness.

Despite warnings to the contrary, a good part of the population of Port City, including a number of families with children, was soon showing up at Maracanda's only spaceport, demanding to be evacuated. When the attackers were already on the ground, interplanetary space seemed like the safest place to be. It was hard to convince these people that all civilian traffic in and out of the system had been halted for the duration of the emergency - any normal shipping arriving in the early warning area was being warned and shuttled away to other ports.

The mere killing of the local population on this peculiar world had always been only a secondary goal for the berserkers. All their work and planning was intended to get their project of mass destruction launched. They would be more intent on defending their work site than attacking the town.

So far, the most intense fighting was concentrated in and around Minersville. Volunteers from Tomb Town had armed themselves and rushed to Minersville to join the fight.

The Space Force office in Port City announced: "We're sending what help we can by caravan, but it'll take days to get there."

Those who elected to stay and fight dug weapons out of storage or tried to improvise them from tools of mining and construction. They set up roadblocks and other kinds of defensive barricades to block the enemy's entrance to the settlements.

The machines that came against them, a few hours later, rolling out of goodlife pedicars and wagons, went quickly through the barriers or around them. The attack was every bit as fierce as an old warrior might have expected, though carried out by only a handful of machines.

The berserker digging machines, pressed into service as combat units, were powerfully destructive, though comparatively slow in both movement and computation. They were also highly resistant to the small arms fire directed against them by the citizens of Tomb Town.

The main thrust of the berserker advance was directed against the power stations and the recycling plants providing local humanity with food and atmosphere. Their destruction would bring on accumulating disaster in a matter of days. So far, volunteers armed with improvised mines and rockets had succeeded in keeping the enemy from those targets.

Almost all Space Force and Templar weapons on the ground had been concentrated, like their people, in and around Port City. The process of reinforcing the eastern settlements had begun, but would take days to complete, with much of the movement restricted to caravan speeds.

The most intrepid badlife among the citizens of Tomb Town had gallantly gone out against the enemy with inferior weapons, and were already dead. A few looters were playing hide-and-seek with death among the mostly deserted and partially ruined buildings of the town.

So far the enemy had found and uprooted all but one of the eastern telegraph terminals. When the last one went, all direct communication east of the caravanserai would be effectively cut off.

The early reports sent west by the humans under attack had understandably exaggerated the numbers of enemy machines, and of the goodlife auxiliaries, too.

People terrified by the berserkers' immediate presence, or just by rumors of their approach, and running for shelter, at least those who had their wits about them, would seek refuge in the deepest breakdown zone they could find.

Some realized that to survive for a matter of days in breakdown, they would have to bring with them substantial supplies of food and water. Others didn't have that much sense.

People who had access to pedicabs, bicycles, tricycles, or similar vehicles, used them to get out of town, and into breakdown sanctuary. But there weren't enough vehicles available to accommodate the entire population. A few were stolen, a few more hijacked.

The flagship of Commandant Rovaki's miniature fleet was a Space Force craft very similar to General Pike's Templar scout-ship. But Pike's colleague and sometime rival was thinking along somewhat different lines.

Rovaki was slow to join in the general radio discussion. When he did, his comments were terse, his questions suspicious. He was still ready to be convinced that somehow Harry Silver was at the bottom of the trouble.

As Pike kept getting garbled reports of events on the surface, he grumbled that the civilians on Maracanda, despite laws and regulations requiring them to do so, had never made any meaningful preparation against a possible berserker attack.

But it was beginning to seem possible that the enemy plan, for anything beyond small-scale assaults on local settlements, had already failed. There was no berserker launch vehicle yet in sight.

Pike had been considering landing his lonely ship again, just long enough to put himself back on the ground, where all the real fighting had been so far. He would delegate command of Templar space operations, such as they were, to a subordinate.

Before doing so he meant to take a close look at the place where, if Silver's and Kochi's warning had any validity, the enemy launch vehicle was scheduled to appear. He would drive his scout-ship, at as low an altitude as he could safely manage, over the eastern part of the habitable zone - or over the place where his instruments indicated that zone must be located. But there was nothing to be seen, except the rugose upper surface of the Maracandan "sky," which seemed to offer nothing but destruction to any ship that tried to pass through it; there was nothing to be done, no way to interact directly with the people and events down there on the ground.

At last, sending an electric jolt through all badlife nervous systems, the dreaded enemy did appear.

When the berserker launch vehicle came shooting up out of that peculiar background, it flew past his scoutship before either he or his autopilot could react effectively, coming so close, within a few kilometers, that Pike instinctively recoiled, as from an imminent collision.

"There it is!"

For the moment, Harry thought it wasn't going to be hard to get a good look at the speeding enemy; in this relatively clear space, the berserker had nothing to hide behind. In ominous accordance with Dr. Kochi's warning, it seemed to have lifted off from the middle of Maracanda's uninhabitable region, and was accelerating fiercely out of an environment where even a berserker ought to find survival difficult.

"That's it, our bandit, the gadget Dr. Kochi's been predicting. What else can it be?"

"There's no doubt it's the berserker launcher. And we have to assume it's carrying several tons of antimatter."

"We must stop it, at all costs, before it gets near Avalon."

Everybody knew that already. But it was easier said than done.

Harry quickly realized that it was going to be hard just to get a good look at the thing. The oddities of intervening space imposed an optical distortion that the onboard computers could not seem to filter out. When Harry managed at last to get the Witch's telescopes zeroed in, he noted that everything in this berserker's construction had a crude and awkward look, which was not surprising, since this particular model was not expected to ever make a soft landing anywhere. He enjoyed a brief interval of clear vision in which it was possible to see that it was skeletal. The exposed innards included a small standard drive unit, good for propulsion and maneuver in normal space, but lacking any transluminal capability. Also lacking, in accordance with what Dr.

Kochi had reported, was anything like a cabin or enclosed space for prisoners or goodlife. And no artificial gravity generator. Any fanatic who had managed to get aboard had doubtless already been thrown free or crushed by relentless acceleration.

Where was the antimatter? Somewhere aboard the hurtling vehicle there must be a package the size of a groundcar. At first Harry thought the berserker was carrying its deadly burden forward, supported ahead of it on two skeletal arms. Then, getting a momentarily clearer look, he spotted a massive, boxlike segment, carried in the rear, where it would be shielded from the ceaseless, high-velocity wind of intrasystem particles by the slender shape of the berserker machine itself.

Harry tried to magnify the image of the package, striving for a better look. "That has to be it. It must be carrying the antimatter inside there."

The voice of Dr. Kochi, soothed and drugged as she now was in the medirobot, had a gentle and mellow sound as she confirmed Harry's conclusion. At her request, the Witch was giving her as good a view as possible of everything that happened.

Hit that compact package with any kind of weapon, Harry was thinking, and it ought to rupture. Swift interaction with the normal matter of the berserker machine itself ought to cause an explosion that might easily wipe out every spacecraft in the system, but save the human lives on Maracanda by preventing the incalculably greater blast the enemy was trying to achieve.

But hitting the package, or even coming close to the berserker itself, proved to be practically impossible. And if there was no way to get close, there clearly was no way to ram.

Lily's eyes were growing frightened. Off radio, she told Harry; "If you only had one more slug for the c-plus, we might be able to do something."

"If your aunt had a mustache, she might be your uncle."

A cycle of commands and exhortations was now making the rounds on badlife radio, all of it to little purpose, as far as Harry could see. The crew of every ship in the system could see what had to be done, but doing it was quite a different story.

Rovaki's ship had somehow fallen behind the others in the chase, and presently he was on radio, wondering aloud if this sortie by the enemy with only a single spacecraft was only some kind of a diversion. Rovaki was already almost a radio-minute behind the Witch, and Harry didn't bother answering.

The warheads of Space Force and Templar missiles aimed at the berserker were going off like fireworks, nuclear and exotic-matter blasts in a random rapid scattering. So far, none of them had come close enough to have any chance of stopping it. Harry had nothing more to contribute to the barrage. The Witch had now entirely used up her modest complement of legal, normal missiles, as well as all the secret c-plus slugs.

A missile from one of the other ships, aimed at the fleeing berserker, came near hitting the Witch instead.

After a minute's delay, Pike's voice came crackling back. "We're trying, Silver. But you've got a better start at heading it off than we have. If you can't hit it with a weapon, we don't have much chance. If it comes down to trying something else, that'll be up to you."

"Naturally." Harry didn't feel in the least bit heroic. The way things were working out, they were all going to be dead in the next few minutes anyway. It wouldn't cost anyone in this system anything to try to save a few billion other people.

"What else is there to try?" Lily asked him, speaking privately.

"I suppose he's talking about ramming it. But if we can't even get close enough to hit it with a beam..."

The berserker was not going to be doing any c-plus jumping, a tactic almost certainly suicidal here near the heart of this crazy system. Nor were the ships now in pursuit. No computer check was needed to confirm that any ship or machine that tried that trick, out of desperation, would be swiftly eliminated without doing its enemies any harm.

Harry was talking to himself - and to Lily, and to the Witch, if either of them cared to listen in. "We don't have to shoot it. We don't have to ram it, in the normal sense. Just touching it, with something, anything, made out of normal matter, ought to be enough."

Avalon was growing larger, in the scope images, and in the cleared ports, too. The stepwise series of concentric orbital shells was actually visible in some wavelengths.

Harry went on radio again. "What am I looking at now? Like rings?"

Someone familiar with the mechanics of the system, most likely Dr. Kochi, watching the proceedings from her berth in the medirobot, explained to Harry that objects in space near this particular pulsar were restricted as to the orbits they were allowed to occupy - almost like electrons orbiting the nucleus of an atom. "It's a form of the Pauli exclusion principle."

"In celestial mechanics? That's crazy."

"I know. But that's how it's going to be when you get very near the star."