The image from the probe was providing better definition as the distance decreased. Drake half expected to see a yellow-streaked globe of sullen red, like Earth when it collapsed to one-tenth of its old size and isolated itself from the rest of the solar system. But he could see surface detail on Felicity. The outline of a single ocean, shaped like a blunt horse's head and low lit by the glancing light of the triple suns, matched the shape shown in the data bank. He saw the softening of texture that indicated the presence of an atmosphere, and occasional high clouds that confirmed it.

"It looks exactly the same." That was Par Leon, muttering his surprise. "Nothing at all seems to have happened to it.

This was one of the worlds that installed our defense systems. Just a month ago, it told us that they were completed and working. So why doesn't it reply to us now?"

Drake could suggest a fistful of answers: * A shield around the planet was inhibiting all outgoing signals or materials; but that clearly could not be the case.

Visible wavelength radiation was being reflected from the surface, since the probe could see it. If necessary, anyone down on the surface could use the same wavelengths to send an outgoing signal.

* A shield was stopping all ingoing signals or materials; but that was even worse. The world below the shield would be in total darkness. Clearly it was not, because sunlight was getting through. In any case, other worlds and colonies affected long ago by such a shield would soon have noticed that they were not receiving messages, and either come or call to ask what was going on.

* Something, a deadly ray or a toxic cloud of gas, had wiped out all life on Felicity. The planet would not at once change its appearance if that happened.

* Something had wiped out all intelligent life. It did not have to be fatal; if humans and their inorganic complements had been reduced to the thinking level of a smart dog, no piece of communications equipment -or any other technology-would mean anything.(Ana, after leaving the home of a couple who swore that their pet was as smart as any human, had said: "No dog, no matter how well bred or well intentioned, can tell you that it came from poor but honest parents. "

He missed her in a thousand ways, but most of all he missed her humor and her refusal to substitute sentiment for sense.) Drake jerked his thoughts back to the task at hand: * The population, for its own reasons, had chosen a policy of total isolationism. If just one world had been affected, that would be wholly plausible. It must have happened a million times. When thousands of neighboring worlds went the same way, though, plausibility became impossibility.

Unless the policy was contagious, an isolationist meme that spread from world to world as a message of irresistible power? But then why hadn't it traveled at superluminal speed and long ago converted the whole Galaxy? And why had the first world affected been far out on the galactic rim? That suggested an influence borne into humanity's domain from far, far away.

Well, they would know soon enough. Felicity was looming right ahead.

"Still no response." Par Leon was losing his nervousness. Drake couldn't understand why. Didn't Leon realize that this scenario must have been played out a million or a billion times, when a ship by an accident of timing had approached a world that had just become silent?

"We propose to land," Leon said. "Do you have any objection?" The probe was swinging into a descent orbit around Felicity's equator. The nightside view showed a scattering of lights. Cities, and a working power system. The planet still showed the signs of an intact civilization.

"None. Carry on with your landing." And good luck, Leon.

Something had to happen, and soon. No ship had ever returned a signal from one of the silent worlds. Either it had never reached the surface, or after it did so it could no longer send a message.

On the other hand, no world had ever to Drake's knowledge possessed its own powerful defenses. Was it as simple as that? Had the defense system done the trick? Was the battle for the Galaxy won already?

He didn't believe it. Too easy, and it would leave a huge mystery. Who and what were the aggressors?

"We still have no descent problems," Leon said. "But there is no navigation signal from the surface. We are going into the final entry phase."

Drake stared at the scene from the probe's imager. No vanished planet. No mysterious shields. Everything as normal as could be.

While that thought was still forming, a bright spark of violet appeared ahead on the line of the equator. It grew rapidly, blossoming from a point to a soft-edged plume of white and blue.

In the final moment before the fire reached up to envelop the probe, and the S-wave message stream to headquarters ceased, Drake understood several things at once.

First, he was going to learn nothing more about present conditions on the surface of Felicity; because the probe, along with Par Leon and the onboard composite, was doomed. They were about to be destroyed by a flame as hot as the center of a star.

Worse than that, humanity was going to learn nothing about the reason why billions of worlds had been silenced.

Whatever had happened to them, it was different from what was happening now on Felicity.

Because the agent for this probe's destruction was not some alien and unknown force. It was part of a human defensive system; a system that had been designed and defined and described to the inhabitants of Felicity by Cass Leemu, Mel Bradley, and Drake Merlin.

This was no time for meeting in ones and twos. Drake could feel the pressure again, the countless terrified minds clamoring at the gates of the villa. They had been calm when the defenses were going into place, blindly hoping that the problem was solved. Was he the only one who had expected the next sector of the Galaxy to fall?-although even he had been shocked when the observing probes were destroyed by the defenses that he had installed.All of his team were assembled in the War Room. They were stunned to silence. The scene that Drake had followed in detail for one probe had been repeated over and over, in a thousand variations. The planets remained apparently untouched and unchanged; but no probe had been able to land.

Par Leon was in the worst shape. It confirmed Drake's idea, that the death of a clone was perfectly real-and not only to the clone. Leon was shattered.

He had seen himself annihilated, time after time. Not one of his copies had tried to do anything about it. Each had gone fatalistically to his doom. It had been a mistake to send Leon, and Drake would not do it again.

He deliberately changed the War Room wall from its overview of newly silenced worlds to the old, white-capped seascape.

"We learned a lot from that experience." He was brisk and businesslike. "Of course, we'll do a full analysis of every case, but I only want Tom involved in that. The rest of you will have other assignments. Milton, we've been treating this as a problem just for humanity. It isn't. Every life-form on a silenced world must be affected. I want to meet with you and review every alien life-form in the Galaxy. We may learn something about the Shiva."

"But it was our understanding that the Shiva originated outside the Galaxy."

The Servitor was as deferential as ever-and as steadfast. Drake realized that Milton would be a better choice than Par Leon to send on future probes. But even Milton would not be ideal. What was needed was someone who would play a long shot, someone to take a wild risk when it was justified.

Who?

Drake postponed the question.

"I think the Shiva did originate from outside the Galaxy," he said. "But even if we don't find out anything about the Shiva from alien life-forms, the forms themselves may prove useful. Leon, I want you to work with Milton on this.

"Melissa, we know that what we tried last time didn't work. If we're going to stop the Shiva spread, we have to know more about how they do it. Can their influence move through open space, or does it need planets to do it efficiently?

You are going to help us answer that question. You will have the job of creating a. firebreak." Drake was forced to use the English word. "Do you know what that is? It's an empty region across the whole Galaxy, surrounding the segment affected by the Shiva. If they need planets, a void should slow and hinder their spread."

Melissa's eyes opened wide, and she shook her head dubiously. "I'll do my best. But do you realize how big a job that will be?"

"It will be enormous. I want a quarantine zone, at least twenty light-years wide, between the edge of the affected sector and the nearest colonized world."

"You mean you want the colonies moved."

"I want more than that. I want the colonies moved to a safer location. But then I want space completely empty in that region. No planets, no stars. Not even dust clouds, if we can do it. I want hard vacuum and nothing else."

"That's impossible."

"I don't think so." Drake turned to Mel Bradley. "You and Cass have been evaluating the caesuras as possible attack weapons. Do you have an idea how big an object they can handle?"

"In principle, there is no limit." Mel had been the last addition to the team, but he was a great choice. While the others cringed at the very idea of violence, he reveled in it. "The caesuras seem to feed on their own activity," he went on.

"The more you put into them, the bigger they get."

"Could you put a whole planet into one?"

"No!" But the hot, angry eyes were gleaming with curiosity. "Not yet, at any rate. We're orders of magnitude away from that. Right now I can put a small asteroid into a caesura. Do you want to put a planet in? Maybe, if we keep going ...".

"Work on it.""And you said stars, too?"

"One step at a time. When you get to the point where a caesura can handle a planet, I want to see a demonstration."

"Mobility is going to be the other problem. We either have to create a caesura where we need it or move one around.

That's not going to be easy."

"Nothing is going to be easy. Get Cass to help you." Drake looked around the table. "All right, I think we've covered everything. Everyone has plenty to do. Let's go do it."

Except, of course, that they had not covered everything. Drake knew it, even if no one else did. He had ducked the most important question of all: Who was going to replace Par Leon as the on-site observer and principal actor in the next interaction with the Shiva?

He knew there would be another interaction. More than that, he expected a countless number of them, over many millennia and even many aeons, before the problem was resolved (one way or another; it might end with the Shiva taking over every world in the Galaxy. That was a resolution of sorts).

Par Leon would not do. He might learn someday to observe dispassionately, but in an emergency he would never know how to take action without direction.

The trouble was, Drake already knew the answer to his own question. It was obvious, as soon as he stated the issues clearly: Who would be willing to use weapons? Who could take a wild risk when it was justified? Who had the most to lose? Who had a motivation to survive, stronger than any of the composites?

The others were terrified when a planet became silent, but any planetary consciousness was likely to form part of a larger composite, with multiple components elsewhere. The disappearance of a planet from the communications web, or even its total annihilation, was not a total death for them. It was more like an amputation, the loss of fingers and toes-highly unpleasant and traumatic, but not fatal.

So. It had to be Drake himself. He would have to agree to something that he had so far resisted, and allow multiple copies of himself to be downloaded, shipped off anywhere that they were needed, and used in either organic or inorganic form. And he had to remain an individual, not joined to form part of a composite. He had to be aware of and afraid of death, focused on his own survival, willing to use any weapon that would allow him to live. Multiple duplication sounded like a guarantee of immortality; he recognized it as a promise of multiple deaths.

He would probably die, over and over, in many places across the Galaxy. Was there any other alternative? If there was, he was not smart enough to see it.

So it had to be Drake. He didn't want to do it, but he would.

He would do it for the sake of Ana, and for their future together.

Chapter 19.

Snark Hunt.

Drake had never felt better; fit, strong, and confident. He narrowed his nostrils against the dusty wind and nodded to Milton. "Ready when you are."

The Servitor was standing by his side. It wore the familiar shape of the wheeled sphere, topped by a whisk broom of motile wires. The wires wriggled and twisted as Milton said, "Are you sure? Do you not need more time to adapt?"

"I am adapted. Perfectly."

"You see, it was easy for me to take on my original form. But in your case ..."Drake knew what the Servitor was getting at. If he thought hard about it, he could recognize that the Sun was a peculiar and brilliant green, two sizes too small in the sky. The landscape of the planet, Graybill, glittered in prismatic silvers and blues. At the limit of vision, the land curved upward to a hazy horizon. He seemed to be standing in a giant bowl that quaked and shivered beneath his feet, like a tough skin stretched tight over viscous jelly.

No problem. Graybill orbited far from a K-type star whose photosphere was peculiarly high in metals. The bowl effect was a result of vastly higher atmospheric pressure. In fact, if he thought about it, he could explain all the things he saw and felt-just as he knew that he inhabited a thick-legged, shorter body, and that other versions of him, thousands or millions of them, existed far, far away.

None of these things mattered. So far as he was concerned, he was the Drake Merlin, the one and only. He suited this body and this world exactly.

"In your case," Milton continued. "I could not employ an exact clone. Your body would not have survived here without modification. It was necessary to download your somatic DNA, perform certain changes to it, then download your acquired database only after body growth was complete. So, even though I suspect that you would have preferred your own original body, as it was on Earth-"

"You can stop apologizing." Drake felt euphoric- dangerously so. Was it possible that Milton had slightly misjudged his body's required gaseous balance? He scratched at his scaly side. "Let's get down to business. Where's the alien?"

"Aliens. Many of them. Far from here. We landed in the equatorial region, and they reside on an isolated continent near the south pole. I wanted to be sure that you were fully operational and adjusted before you were exposed to danger."

"That bad?"

"Or good. It is a matter of definition. Let me say this: I have examined more than fourteen thousand other alien life-forms that fulfill some or all of the qualifications for sentience. Never, however, have I encountered one so feral and vicious."

"And intelligent?"

"Not in technological terms. The Snarks use no tools. They have not mastered fire. They modify their environment only in the simplest ways. They seem to possess no language."

"But you still say they are dangerous?"

"I know that they are." Milton led the way from the main ship to a smaller, wingless vehicle that rested on the glittering and shaking surface. "This is your third embodiment on this planet."

"What happened to the other two?"

It was a stupid question, and one that Milton was not supposed to answer. It was a rule that Drake himself had set up: each of his encounters with an alien would be judged on its own merits. Milton would be fully aware of the prior failed experiences, but Drake would not. It had been the same with the fourteen thousand cases. Drake-or one of his embodiments-must have met each of them, but apart from generalities all he knew was that none was useful against the Shiva.

Now the Servitor said only, ' 'This time we are taking special precautions. They included landing far from the polar continent and all Snarks, until I was sure that you were totally at home with your embodiment."

No more information; except that a knowledge of two prior failures was itself information. On the twenty-minute suborbital flight toward Graybill's pole, Drake sat and wondered. What had he done the previous times to get himself killed? Would he be killed again? If so, it would be no less painful, merely because it had happened before.

The ship landed on a coastline that crawled with warm-blooded and active plants. Drake could feel a sharp drop in temperature, but his body remained quite comfortable. He merely felt a tightening in his outer layers as improved thermal insulation went into action. He walked to the waterline, knowing that it was not actually water. Any water was in solid form, lying on the bottom. This was some mix of alcohols and hydrocarbons, heptane and ether and propanol, all lighter than water ice.

He bent and scooped up a handful to his tendril-fringed mouth. It tasted fine.

"That way." Milton was pointing as Drake straightened up. "About seven kilometers inland you will find the firstSnark nests. Do you wish me to accompany you?"

Milton's voice was hopeful. Drake shook his scaled , and snouted head. The Servitor was smart, but some things it would never learn. There was no way that Milton could remain quiet if Drake was moving into danger. Not only that, no matter how much Drake discouraged it, the Servitor could not help giving hints designed to keep Drake out of danger. It was not Milton's fault. The Servitor was designed to protect and safeguard Drake Merlin. Its present role of bystander was more than it could stand.

Drake reinforced his gesture with words. "You stay right here until I come back. Don't leave the flier."

The wiry whisk broom contorted and turned uneasily. "That is what you said on the last occasion we were here."

More information that Drake was not supposed to have. "So I'm saying it again. If I am not back by dark, you can come looking for me."

"That will be a very long time. We are in the polar regions, and this is summer."

"One quarter of a planetary revolution period, then. If I'm not back in that time, come and pick up the pieces. But not before. I don't want you around when I'm at the nests. Remember, they also serve who only stand and wait." Drake headed inland. Milton was tireless and careful and conscientious, but sometimes the Servitor could be a real pain.

Seven kilometers: it sounded like a reasonable safety margin; except that he had no idea what senses were available to the Snarks. Vision by short wavelength light was the most commonly used sense in the Galaxy, evidence of the fact that the average main sequence star emits peak energy at a wavelength between one-half and one micron. However, a dozen other senses were in general use wherever there was an atmosphere: hearing, thermal infrared detection, direct monitoring of magnetic and electric fields, echo location, smell-the Snarks might use any or all of these. Back on ancient Earth, a polar bear could sniff a dead whale thirty kilometers away. A mating moth could identify its distant partner from a single molecule of pheromone. The Snarks might already be aware of Drake.

The ground was becoming increasingly rock strewn and broken, large boulders separated by stretches of flat gravel covered with slow-moving blue ferns. Drake reduced his pace at the two-kilometer mark and again as he caught his first glimpse of what must be the nests. They were well separated, each one long and thin and hollow, like a section of wide clay pipe laid on its side. He could see no sign of life there, but he stopped, crouched down onto his thick haunches, and waited. As soon as he was stationary, the warm-blooded vegetation crawled doggedly to his feet and around them. Tendrils like gentle blue fingers reached up, touched his legs, and apparently decided that he had no potential as a nutrient source. The warm fingers dropped back. The plants crept away.

At last, Drake could see something moving near the clay pipes. Would he have been so patient, without Milton's warning of earlier problems? Surely not. He would have kept going, because the things that he could see ahead moved not much faster than the plants.

There were scores of them. The Snarks were fat white segmented cylinders, supported by scores of slender white pseudopods. The bodies were about five feet long and a foot and a half wide. The head end, as judged from the direction that they moved, lacked all distinguishing marks. A curving tail of darker creamy-white arched up over the back to direct its sharp tip forward. The pointed end moved slowly from side to side. Did it, rather than the "head,"

house the sense organs? Perhaps that was the head, and a Snark walked backward.

The Snarks seemed to take no notice of each other or of their surroundings, but as he watched, four of them reared up slowly from their horizontal positions. Each blind head curved back until it met the tail and formed a complete loop.