Intent upon joining Sssuri, Dalgard left the lock, forgetting his earlier unwillingness, stepping from the small chamber down to the sea bottom, or endeavoring to, although instinctively he had begun to swim and so forged ahead at a different rate of speed.

Waving fronds of giant water plants, such as were found only in the coastal shallows, grew forest fashion but did not hide rocks which stretched up in a sharp rise not too far ahead. The scout could not see the merman, but as he held onto one of those fronds he caught the other's summons:

"Here—by the rocks—!"

Pushing his way through the drifting foliage, Dalgard swam ahead to the foot of the rocky escarpment. And there he saw what had so excited his companion.

Sssuri had just driven away an encircling collection of sand-dwelling scavengers, and what he was on his knees studying intently was an almost clean-picked skeleton of one of his own race. But there was something odd—Dalgard brushed aside a tendril of weed which cut his line of vision and so was able to see clearly.

White and clean most of those bones were, but the skull was blackened, and similar charring existed down one arm and shoulder. That merman had not died from any mishap in the sea!

"It is so," Sssuri replied to his thought. "They have come once more to give the flaming death—"

Dalgard, startled, looked up that slope which must lead to the island top above the waves.

"Long dead?" he asked tentatively, already guessing what the other's answer would be.

"The pickers move fast," Sssuri indicated the sand dwellers. "Perhaps yesterday, perhaps the day before—but no longer than that."

"And they are up there now?"

"Who can tell? However, they do not know the sea, nor the islands—"

It was plain that the merman intended to climb to investigate what might be happening above. Dalgard had no choice but to follow. And it was true that the merpeople had no peers or equals when it came to finding their ways about the sea and the coasts. He was confident that Sssuri could get to the island top and discover just what he wished to learn without a single sentry above, if they had stationed sentries, being the wiser. Whether he himself could operate as efficiently was another matter.

In the end they half climbed, half swam upward, detouring swiftly once to avoid the darting attack of a rock hornet, harmless as soon as they moved out of the reach of its questing stinger, for it was anchored for its short life to the rough hollow in which it had been hatched.

Dalgard's head broke water as he rolled through the surf onto a scrap of beach in the lee of a row of tooth-pointed outcrops. It was late evening by the light, and he clawed the mask off his face to draw thankful lungfuls of the good outer air. Sssuri, his fur sleeked tight to his body, waded ashore, shook himself free of excess water, and turned immediately to study the wall of the cliff which guarded the interior of the island.

This was one of a chain of such isles, Dalgard noted, now that he had had time to look about him. And with their many-creviced walls they were just the type of habitations which appealed most strongly to the merpeople. Here could be found the dry inner caves with underwater entrances, which they favored for their group homes. And in the sea were kelp beds for harvesting.

The cliffs did not present too much of a climbing problem. Dalgard divested himself of the diving equipment, tucking it into a hollow which he walled up with stones that he thought the waves would not scour out in a hurry. He might need it again. Then, hitching his belt tighter, pressing what water he could out of his clothing, and settling his bow and quiver to the best advantage at his back, he crossed to where Sssuri was already marking claw holds.

"We may be seen—" Dalgard craned his neck, trying to make out details of what might be waiting above.

The merman shook his head with a quick jerk of negation. "They are gone. Behind them remains only death—much death—" And the bleakness of his thoughts reached the scout.

Dalgard had known Sssuri since he was a toddler and the other a cub coming to see the wonders of dry land for the first time. Never, during all their years of close association since, had he felt in the other a desolation so great. And to that emotional blast he could make no answer.

In the twilight, with the last red banners across the sky at their back, they made the climb. And it was as if the merman had closed off his mind to his companion. Flesh fingers touched scaled ones as they moved from one hold to the next, but Sssuri might have been half a world away for all the communication between them. Never had Dalgard been so shut out and with that his sensitivity to the night, to the world about him, was doubly acute.

He realized—and it worried him—that perhaps he had come to depend too much on Sssuri's superior faculty of communication. It was time that he tried to use his own weaker powers to the utmost extent. So, while he climbed, Dalgard sent questing thoughts into the gloom. He located a nest of duck-dogs, those shy waterline fishers living in cliff holes. They were harmless and just settling down for the night. But of higher types of animals from which something might be learned—hoppers, runners—there were no traces. For all he was able to pick up, they might be climbing into blank nothingness.

And that in itself was ominous. Normally he should have been able to mind touch more than duck-dogs. The merpeople lived in peace with most of the higher fauna of their world, and a colony of hoppers, even a covey of moth birds, would settle in close by a mer tribe to garner in the remnants of feasts and for protection from the flying dragons and the other dangers they must face.

"They hunt all life," the first break in Sssuri's self-absorption came. "Where they walk the little, harmless peoples face only death. And so it has been here." He had pulled himself over the rim of the cliff, and through the dark Dalgard could hear him panting with the same effort which made his own lungs labor.

Just as the stench of the snake-devil's lair had betrayed its site, here disaster and death had an odor of its own. Dalgard retched before he could control throat and stomach muscles. But Sssuri was unmoved, as if he had expected this.

Then, to Dalgard's surprise the merman set up the first real call he had ever heard issue from that furred throat, a plaintive whistle which had a crooning, summoning note in it, akin to the mind touch in an odd fashion, yet audible. They sat in silence for a long moment, the human's ears as keen for any sound out of the night as those of his companion. Why did Sssuri not use the customary noiseless greeting of his race? When he beamed that inquiry, he met once again that strange, solid wall of non-acceptance which had enclosed the merman as they climbed. As if now there was danger to be feared from following the normal ways.

Again Sssuri whistled, and in that cry Dalgard heard a close resemblance to the flute tone of the night moth birds. Up the scale the notes ran with mournful persistence. When the answer came, the scout at first thought that the imitation had lured a moth bird, for the reply seemed to ripple right above their heads.

Sssuri stood up, and his hand dropped on Dalgard's shoulder, applying pressure which was both a warning and a summons, bringing the scout to his feet with as little noise as possible. The horrible smell caught at his throat, and he was glad when the merman did not head inland toward the source of that odor, but started off along the edge of the cliff, one hand in Dalgard's to draw him along.

Twice more Sssuri paused to whistle, and each time he was answered by a signing note or two which seemed to reassure him.

Against the lighter expanse which was the sea, Dalgard saw the loom of a peak which projected above file general level of the island. Though he knew that the merpeople did not build aboveground, being adept in turning natural caves and crevices into the kind of living quarters they found most satisfactory, the barrenness of this particular rock top was forbidding.

Led by Sssuri, he threaded a tangled patch among outcrops, once-squeezing through a gap which scraped the flesh on his arms as he wriggled. Then the sky was blotted out, the last winking star disappeared, and he realized that he must have entered a cave of sorts, or was at least under an overhang.

The merman did not pause but padded on, tugging Dalgard along, the scout's boots scraping on the rough footing. The colonist was conscious now that they were on an incline, heading down into the heart of the island. They came to a stretch where Sssuri set his hands on holds, patiently shoved his feet into hollowed places, finding for him the ladder steps he could not see, which took him through a sweating, fearful journey of yards to another level, another sloping, downward way.

Here at long last was a fraction of light, not the violet glimmer which had illuminated the underground ways of those Others, but a ghostly radiance which he recognized as the lamps of the mermen—living creatures from the sea depths imprisoned in laboriously fashioned globes of crystal and kept in the caves for the light they yielded.

But still no mind touch! Never had Dalgard penetrated into the cave cities of the sea folk before without inquiries and open welcome lapping about him. Were they entering a place of massacre where no living merman remained? Yet there was that whistling which had led Sssuri to this place....

And at that moment a shrill keening note arose from the depths to ring in Dalgard's ears, startling him so that he almost lost his footing. Once again Sssuri made answer vocally—but no mind touch.

Then they rounded a curve, and the scout was able to see into the heart of the amphibian territory. This was a natural cave, as were all the merman's dwellings, but its walls had been smoothed and hung with the garlands of shells which they wove in their leisure into strange pictures. Silver-gray sand, smooth and dust-fine, covered the floor to the depth of a foot or more. And opening off the main chamber were small nooks, each marking the private storage place and holding of some family clan. It was a large place, and with a quick estimate Dalgard thought that it had been fashioned to harbor close to a hundred inhabitants, at least the nooks suggested that many. But gathered at the foot of the ledge they were descending, spears poised, were perhaps ten males, some hardly past cubhood, others showing the snowy shine of fur which was the badge of age. And behind them, drawn knives in their ready hands, were half again as many merwomen, forming a protecting wall before a crouching group of cubs.

Sssuri spoke to Dalgard. "Spread out your hands—empty—so that they may see them clearly!"

The scout obeyed. In the limited light his ten fingers were fans, and it was then that he understood the reason for such a move. If these mermen had not seen a colonist before, he might resemble Those Others in their eyes. But only his species on all Astra had five fingers, five toes, and that physical evidence might insure his safety now.

"Why do you bring a destroyer among us? Or do you offer him for our punishment, so that we can lay upon him the doom that his kind have earned?"

The question came with arrow force, and Dalgard held out his hands, hoping they would see the difference before one of those spears from below tore through his flesh.

"Look upon the hands of this—my knife brother—look upon his face. He is not of the race of those you hate, but rather one from the south. Have you of the northern reaches not heard of Those-Who-Help, Those-Who-Came-From-the-Stars?"

"We have heard." But there was no relaxing of tension, not a spear point wavered.

"Look upon his hands," Sssuri insisted. "Come into his mind, for he speaks with us so. And do they do that?"

Dalgard tried to throw open his mind, awaiting the trial. It came quickly, traces of inimical, alien thought, which changed as they touched his mind, reading there only all the friendliness he and his held for the sea people.

"He is not of them." The admission was grudging. As if they did not want to believe that. "Why comes one from the south to this place—now?"

There was an inflection to that "now" which was disturbing.

"After the manner of his people he seeks new things so that he may return and report to his Elders. Then he will receive the spear of manhood and be ready for the choosing of mates," Sssuri translated the reason for Dalgard's quest into the terms of his own people. "He has been my knife brother since we were cubs together, and so I journey with him. But here in the north we have found evil—"

His flow of thought was submerged by a band of hate so red that its impact upon the mind was almost a blow. Dalgard shook his head. He had known that the merpeople, aroused, were deadly fighters, fearless and crafty, and with a staying power beyond that of any human. But their rage was something he had not met before.

"They come once again—they burn with the fire—They are among our islands—"

A cub whimpered and a merwoman stooped to pat it to silence.

"Here they have killed with the fire—"

They did not elaborate upon that statement, and Dalgard had no wish for them to do so. He was still very glad that it had been dark when he had climbed to the top of that cliff, that he had not been able to see what his imagination told him lay there.

"Do they stay?" That was Sssuri.

"Not so. In their sky traveler they go to the land where lies the dark city. There they make much evil against the day when this shall be their land once more."

"But these lie if they think that." Another strong thought broke across the current of communication. "We are not now penned for their pleasure. We may flee into the sea once more, and there live as did our fathers' fathers, and they dare not follow us there—"

"Who knows?" It was Sssuri who raised that objection. "With their ancient knowledge once more theirs, even the depths of the sea may not be ours much longer. Do they not know how to ride upon the air?"

The knot of mer-warriors stirred. Several spears thudded butt down into the sand. And Sssuri accepted that as an invitation to descend, summoning Dalgard after him with a beckoning finger.

Later they sat in a circle in the cushioning gray powder, the two from the south eating dried fish and sea kelp, while Sssuri related, between mouthfuls, their recent adventures.

"Three times have they flown across these islands on their way to that city," the Elder of the pitifully decimated merman tribe told the explorers.

"But this time," broke in one of his companions, "they had with them a new ship—"

"A new ship?" Sssuri pounced upon that scrap of information.

"Yes. The ships of the air in which they travel are fashioned so"—with his knife point he drew a circle in the sand—"but this one was smaller and more in the likeness of a spear with a heavy point—thus"—he made a second sketch beside the first, and Dalgard and Sssuri leaned over to study it.

"That is unlike any of their ships that I have heard of," Sssuri agreed. "Even in the old tales of the Days Before the Burning there is nothing spoken of like that."

"It is true. Therefore we wait now for the coming of our scouts, who were set in hiding upon their sea rock of resting, that they may tell us more concerning this new ship. They should be here within this time of sleeping. Now, go you to rest, which you plainly have need of, and we shall call you when they come."

Dalgard was willing enough to stretch out in the sand in the shadows of the far end of the cave. Beyond him three cubs slumbered together, their arms about each other, and a feeling of peace was there such as he had not known since he left the stronghold of Homeport.

The weird glow of the imprisoned sea monsters gave light to the main part of the cave, and it might still have been night when the scout was shaken awake once more. A group of the merpeople were sitting together, and their thoughts interrupted each other as their excitement arose. Their spies must have returned.

Dalgard crossed to join that group, but it seemed to him that his welcome was not unqualified, and that some of the openness of the early hours of the night was lacking. He might have been once more under suspicion.

"Knife brother"—to Dalgard's sensitive mind that form of address from Sssuri was used for a special purpose: to underline the close bond between them—"listen to the words of Sssim who is a Hider-to-Watch on the island where they rest their ships during the voyage from one land to another." He drew Dalgard down beside him to face a young merman who was staring round-eyed at the colony scout.

"He is like—yet unlike"—his first wisp of thought meant nothing to the scout. "The strangers wear many coverings on their bodies as do they, and they had also coverings upon their heads. They were bigger. Also from their minds I learned that they are not of this world—"

"Not of this world!" Dalgard burst out in his own speech.

"There!" The spy was triumphant. "So did they talk to one another, not with the mind but by making mouth noises, different mouth noises from those that they make. Yes, they are like—but unlike this one."

"And these strangers flew the ship we have not seen before?"

"It is so. But they did not know the way and were guided by the globe. And at least one among them was distrustful of those and wished to be free to return to his own place. He walked by the rocks near my hiding place, and I read his thoughts. No, they were with them, but they are not them!"

"And now they have gone on to the city?" Sssuri probed.

"It was the way their ship flew."

"Like me," Dalgard repeated, and then the truth which might lie behind that exploded within his brain. "Terrans!" he breathed the word. Men of Pax perhaps who had come to hunt down the outlaws who had successfully eluded their rule on earth? But how had the colonists been traced? And why? Or were they other fugitives like themselves? So much, so very much of what the colonists should know of their past had been erased during the time of the Great Sickness twenty years after their landing. Then three fourths of the original immigrants had died. Only the children of the second generation and a handful of weakened Elders had remained. Knowledge was lost and some distorted by failing memories, old skills were gone. But if the new Terrans were in that city.... He had to know—to know and be able to warn his people. For the darkness of Pax was a memory they had not lost!

"I must see them," he said.

"That is true. And only you can tell us what manner of folk these strangers be," the merman chief agreed. "Therefore you shall go ashore with my warriors and look upon them—to tell us the truth. Also we must learn what they do here."

It was decided that using waterways known to the merpeople, one which Dalgard could also take wearing the diving equipment, a scouting party would head shoreward the next day, with the river itself providing the entrance into the heart of the forbidden territory.