Dalgard's feet touched gravel; he waded cautiously to the bank, where a bridge across the river made a concealing shadow on the water. None of the mermen had accompanied him this far. Sssuri, as soon as his human comrade had started for the storage city, had turned south to warn and rally the tribes. And the merpeople of the islands had instituted a loose chain of communication, which led from a clump of water reeds some two miles back to the seashore, and so out to the islands. Better than any of the now legendary coms of his Terran forefathers were these minds of the spies in hiding, who could pick up the racing thoughts beamed to them and pass them on to their fellows.

Although there were no signs of life about the city, Dalgard moved with the same care that he would have used in penetrating a snake-devil's lair. In the first hour of dawn he had contacted a hopper. The small beast had been frightened almost out of coherent thought, and Dalgard had had to spend some time in allaying that terror to get a fractional idea of what might be going on in this countryside.

Death—the hopper's terror had come close to insanity. Killers had come out of the sky, and they were burning—burning—All living things were fleeing before them. And in that moment Dalgard had been forced to give up his plan for an unseen spy ring, which would depend upon the assistance of the animals. His information must come via his own eyes and ears.

So he kept on, posting the last of the mermen in his mental relay well away from the city, but swimming upstream himself. Now that he was here, he could see no traces of the invaders. Since they could not have landed their sky ships in the thickly built-up section about the river, it must follow that their camp lay on the outskirts of the metropolis.

He pulled himself out of the water. Bow and arrows had been left behind with the last merman; he had only his sword-knife for protection. But he was not there to fight, only to watch and wait. Pressing the excess moisture out of his scant clothing, he crept along the shore. If the strangers were using the streets, it might be well to get above them. Speculatively he eyed the buildings about him as he entered the city.

Dalgard continued to keep at street level for two blocks, darting from doorway to shadowed doorway, alert not only to any sound but to any flicker of thought. He was reasonably sure, however, that the aliens would be watching and seeking only for the merpeople. Though they were not telepathic as their former slaves, Those Others were able to sense the near presence of a merman, so that the sea people dared not communicate while within danger range of the aliens without betraying themselves. It was the fact that he was of a different species, therefore possibly immune to such detection, which had brought Dalgard into the city.

He studied the buildings ahead. Among them was a cone-shaped structure which might have been the base of a tower that had had all stories above the third summarily amputated. It was ornamented with a series of bands in high relief, bands bearing the color script of the aliens. This was the nearest answer to his problem. However the scout did not move toward it until after a long moment of both visual and mental inspection of his surroundings. But that inspection did not reach some twelve streets away where another crouched to watch. Dalgard ran lightly to the tower at the same moment that Raf shifted his weight from one foot to the other behind a parapet as he spied upon the knot of aliens gathered below him in the street....

The pilot had followed them since that early morning hour when Soriki had awakened him. Not that the chase had led him far in distance. Most of the time he had spent in waiting just as he was doing now. At first he had believed that they were searching for something, for they had ventured into several buildings, each time to emerge conferring, only to hunt out another and invade it. Since they always returned with empty hands, he could not believe that they were out for further loot. Also they moved with more confidence than they had shown the day before. That confidence led Raf to climb above them so that he could watch them with less chance of being seen in return.

It had been almost noon when they had at last come into this section. If two of them had not remained idling on the street as the long moments crept by, he would have believed that they had given him the slip, that he was now a cat watching a deserted mouse hole. But at the moment they were coming back, carrying something.

Raf leaned as far over the parapet as he dared, trying to catch a better look at the flat, boxlike object two of them had deposited on the pavement. Whatever it was either needed some adjustment or they were attempting to open it with poor success, for they had been busied about it for what seemed an unusually long time. The pilot licked dry lips and wondered what would happen if he swung down there and just walked in for a look-see. That idea was hardening into resolution when suddenly the group below drew quickly apart, leaving the box sitting alone as they formed a circle about it.

There was a puff of white vapor, a protesting squawk, and the thing began to rise in jerks as if some giant in the sky was pulling at it spasmodically. Raf jumped back. Before he could return to his vantage point, he saw it rise above the edge of the parapet, reach a level five or six feet above his head, hovering there. It no longer climbed; instead it began to swing back and forth, describing in each swing a wider stretch of space.

Back and forth—watching it closely made him almost dizzy. What was its purpose? Was it a detection device, to locate him? Raf's hand went to his stun gun. What effect its rays might have on the box he had no way of knowing, but at that moment he was sorely tempted to try the beam out, with the oscillating machine as his target.

The motion of the floating black thing became less violent, its swoop smoother as if some long-idle motor was now working more as its builders had intended it to perform. The swing made wide circles, graceful glides as the thing explored the air currents.

Searching—it was plainly searching for something. Just as plainly it could not be hunting for him, for his presence on that roof would have been uncovered at once. But the machine was—it must be—out of sight of the warriors in the street. How could they keep in touch with it if it located what they sought? Unless it had some built-in signaling device.

Determined to keep it in sight, Raf risked a jump from the parapet of the building where he had taken cover to another roof beyond, running lightly across that as the hound bobbed and twisted, away from its masters, out across the city in pursuit of some mysterious quarry....

The climb which had looked so easy from the street proved to be more difficult when Dalgard actually made it. His hours of swimming in the river, the night of broken rest, had drained his strength more than he had known. He was panting as he flattened himself against the wall, his feet on one of the protruding bands of colored carving, content to rest before reaching for another hold. To all appearances the city about him was empty of life and, except for the certainty of the merpeople that the alien ship and its strange companion had landed here, he would have believed that he was on a fruitless quest.

Grimly, his lower lip caught between his teeth, the scout began to climb once more, the sun hot on his body, drawing sweat to dampen his forehead and his hands. He did not pause again but kept on until he stood on the top of the shortened tower. The roof here was not flat but sloped inward to a cuplike depression, where he could see the outline of a round opening, perhaps a door of sorts. But at that moment he was too winded to do more than rest.

There was a drowsiness in that air. He was tempted to curl up where he sat and turn his rest into the sleep his body craved. It was in that second or so of time when he was beginning to relax, to forget the tenseness which had gripped him since his return to this ill-omened place, that he touched—

Dalgard stiffened as if one of his own poisoned arrows had pricked his skin. Rapport with the merpeople, with the hoppers and the runners, was easy, familiar. But this was no such touch. It was like contacting something which was icy cold, inimical from birth, something which he could never meet on a plain of understanding. He snapped off mind questing at that instant and huddled where he was, staring up into the blank turquoise of the sky, waiting—for what he did not know. Unless it was for that other mind to follow and ferret out his hiding place, to turn him inside out and wring from him everything he ever knew or hoped to learn.

As time passed in long breaths, and he was not so invaded, he began to think that while he had been aware of contact, the other had not. And, emboldened, he sent out a tracer. Unconsciously, as the tracer groped, he pivoted his body. It lay—there!

At the second touch he withdrew in the same second, afraid of revelation. But as he returned to probe delicately, ready to flee at the first hint that the other suspected, his belief in temporary safety grew. To his disappointment he could not pierce beyond the outer wall of identity. There was a living creature of a high rate of intelligence, a creature alien to his own thought processes, not too far away. And though his attempts to enter into closer communication grew bolder, he could not crack the barrier which kept them apart. He had long known that contact with the merpeople was on a lower, a far lower, band than they used when among themselves, and that they were only able to "talk" with the colonists because for generations they had exchanged thought symbols with the hoppers and other unlike species. They had been frank in admitting that while Those Others could be aware of their presence through telepathic means, they could not exchange thoughts. So now, his own band, basically strange to this planet, might well go unnoticed by the once dominant race of Astra.

They—or him—or it—were over in that direction, Dalgard was sure of that. He faced northwest and saw for the first time, about a mile away, the swelling of the globe. If the strange flyer reported by the merpeople was beside it, he could not distinguish it from this distance. Yet he was sure the mind he had located was closer to him than that ship.

Then he saw it—a black object rising by stiff jerks into the air as if it were being dragged upward against its inclination. It was too small to be a flyer of any sort. Long ago the colonists had patched together a physical description of Those Others which had assured them that the aliens were close to them in general characteristics and size. No, that couldn't be carrying a passenger. Then what—or why?

The object swung out in a gradually widening circle. Dalgard held to the walled edge of the roof. Something within him suggested that it would be wiser to seek some less open space, that there was danger in that flying box. He released his hold and went to the trap door. It took only a minute to fit his fingers into round holes and tug. Its stubborn resistance gave, and stale air whooshed out in his face as it opened.

In his battle with the door Dalgard had ignored the box, so he was startled when, with a piercing whistle, almost too high on the scale for his ears to catch, the thing suddenly swooped into a screaming dive, apparently heading straight for him. Dalgard flung himself through the trap door, luckily landing on one of the steep, curved ramps. He lost his balance and slid down into the dark, trying to brake his descent with his hands, the eerie screech of the box trumpeting in his ears.

There was little light in this section of the cone building, and he was brought up with bruising force against a blank wall two floors below where he had so unceremoniously entered. As he lay in the dark trying to gasp some breath back into his lungs, he could still hear the squeal. Was it summoning? There was no time to be lost in getting away.

On his hands and knees the scout crept along what must have been a short hall until he found a second descending ramp, this one less steep than the first, so that he was able to keep to his feet while using it. And the gloom of the next floor was broken by odd scraps of light which showed through pierced portions of the decorative bands. The door was there, a locking bar across it.

Dalgard did not try to shift that at once, although he laid his hands upon it. If the box was a hound for hunters, had it already drawn its masters to this building? Would he open the door only to be faced by the danger he wished most to avoid? Desperately he tried to probe with the mind touch. But he could not find the alien band. Was that because the hunters could control their minds as they crept up? His kind knew so little of Those Others, and the merpeople's hatred of their ancient masters was so great that they tended to avoid rather than study them.

The scout's sixth sense told him that nothing waited outside. But the longer he lingered with that beacon overhead the slimmer his chances would be. He must move and quickly. Sliding back the bar, he opened the door a crack and looked out into a deserted street. There was another doorway to take shelter in some ten feet or so farther along, beyond that an alley wall overhung by a balcony. He marked these refuges and went out to make his first dash to safety.

Nothing stirred, and he sprinted. There came again that piercing shriek to tear his ears as the floating box dived at him. He swerved away from the doorway to dart on under the balcony, sure now that he must keep moving, but under cover so that the black thing could not pounce. If he could find some entrance into the underground ways such as those that ran from the arena—But now he was not even sure in which direction the arena stood, and he dared no longer climb to look over the surrounding territory.

He touched the alien mind! They were moving in, following the lead of their hound. He must not allow himself to be cornered. The scout fought down a surge of panic, attempted to battle the tenseness which tied his nerves. He must not run mindlessly either. That was probably just what they wanted him to do. So he stood under the balcony and tried not to listen to the shrilling of the box as he studied the strip of alley.

This was a narrow side way, and he had not made the wisest of choices in entering it, for not much farther ahead it was bordered with smooth walls protecting what had once been gardens. He had no way of telling whether the box would actually attack him if he were caught in the open—to put that to the test was foolhardy—nor could he judge its speed of movement.

The walls.... A breeze which blew up the lane carried with it the smell of the river. There was a slim chance that it might end in water, and he had a feeling that if he could reach the stream he would be able to baffle the hunters. He did not have long to make up his mind—the aliens were closer.

Lightly Dalgard ran under the length of the balcony, turned sharply as he reached the end of its protecting cover, and leaped. His fingers gripped the ornamental grillwork, and he was able to pull himself up and over to the narrow runway. A canopy was still over his head, and there came a bump against it as the baffled box thumped. So it would try to knock him off if it could get the chance! That was worth knowing.

He looked over the walls. They guarded masses of tangled vegetation grown through years of neglect into thick mats. And those promised a way of escape, if he could reach them. He studied the windows, the door opening onto the balcony. With the hilt of his sword-knife he smashed his way into the house, to course swiftly through the rooms to the lower floor, and find the entrance to the garden.

Facing that briary jungle on the ground level was a little daunting. To get through it would be a matter of cutting his way. Could he do it and escape that bobbing, shrilling thing in the air? A trace of pebbled path gave him a ghost of a chance, and he knew that these shrubs tended to grow upward and not mass until they were several feet above the ground.

Trusting to luck, Dalgard burrowed into the green mass, slashing with his knife at anything which denied him entrance. He was swallowed up in a strange dim world wherein dead shrubs and living were twined together to form a roof, cutting off the light and heat of the sun. From the sour earth, sliming his hands and knees, arose an overpowering stench of decay and disturbed mold. In the dusk he had to wait for his eyes to adjust before he could mark the line of the old path he had taken for his guide.

Fortunately, after the first few feet, he discovered that the tunneled path was less obstructed than he had feared. The thick mat overhead had kept the sun from the ground and killed off all the lesser plants so that it was possible to creep along a fairly open strip. He was conscious of the chitter of insects, but no animals lingered here. Under him the ground grew more moist and the mold was close to mud in consistency. He dared to hope that this meant he was either approaching the river or some garden stream feeding into the larger flood.

Somewhere the squeal of the hunter kept up a steady cry, but, unless the foliage above him was distorting that sound, Dalgard believed that the box was no longer directly above him. Had he in some way thrown it off his trail?

He found his stream, a thread of water, hardly more than a series of scummy pools with the vegetation still meeting almost solidly over it. And it brought him to a wall with a drain through which he was sure he could crawl. Disliking to venture into that cramped darkness, but seeing no other way out, the scout squirmed forward in slime and muck, feeling the rasp of rough stone on his shoulders as he made his worm's progress into the unknown.

Once he was forced to halt and, in the dark, loosen and pick out stones embedded in the mud bottom narrowing the passage. On the other side of that danger point, he was free to wriggle on. Could the box trace him now? He had no idea of the principle on which it operated; he could only hope.

Then before him he saw the ghostly gray of light and squirmed with renewed vigor—to be faced then by a grille, beyond which was the open world. Once more his knife came into use as he pried and dug at the barrier. He worked for long moments until the grille splashed out into the sluggish current a foot or so below, and then he made ready to lower himself into the same flood.

It was only because he was a trained hunter that he avoided death in that moment. Some instinct made him dodge even as he slipped through, and the hurtling black box did not strike true at the base of his brain but raked along his scalp, tearing the flesh and sending him tumbling unconscious into the brown water.