Dalgard drew the waterproof covering back over his brow, making a cheerful job of it, preparatory to their pushing out to sea once more. But he was as intent upon what Sssuri had to tell as he was on his occupation of the moment.

"But that is not even a hopper rumor," he was protesting, breaking into his companion's flow of thought.

"No. But, remember, to the runners yesterday is very far away. One night is like another; they do not reckon time as we do, nor lay up memories for future guidance. They left their native hunting grounds and are drifting south. And only a very great peril would lead the runners into such a break. It is against all their instincts!"

"So, long ago—which may be months, weeks, or just days—there came death out of the sea, and those who lived past its coming fled—" Dalgard repeated the scanty information Sssuri had won for them the night before by patient hour-long coaxing. "What kind of death?"

Sssuri's great eyes, somber and a little tired, met his. "To us there is only one kind of death to be greatly feared."

"But there are the snake-devils—" protested the colony scout.

"To be hunted down by snake-devils is death, yes. But it is a quick death, a death which can come to any living thing that is not swift or wary enough. For to the snake-devils all things that live and move are merely meat to fill the aching pit in their swollen bellies. But there were in the old days other deaths, far worse than what one meets under a snake-devil's claws and fangs. And those are the deaths we fear." He was running the smooth haft of his spear back and forth through his fingers as if testing the balance of the weapon because the time was not far away when he must rely upon it.

"Those Others!" Dalgard shaped the words with his lips as well as in his mind.

"Just so." Sssuri did not nod, but his thought was in complete agreement.

"Yet they have not come before—not since the ship of my fathers landed here," Dalgard protested, not against Sssuri's judgment but against the whole idea.

The merman got to his feet, sweeping his arm to indicate not only the cove where they now sheltered but the continent behind it.

"Once they held all this. Then they warred and killed, until but a handful lay in cover to lick their wounds and wait. It has been many threes of seasons since they left that cover. But now they come again—to loot their place of secrets—Perhaps in the time past they have forgotten much so that now they must renew their knowledge."

Dalgard stowed the bow in the bottom of the outrigger. "I think we had better go and see," he commented, "so that we may report true tidings to our Elders—something more than rumors learned from night runners."

"That is so."

They paddled out to sea and turned the prow of the light craft north. The character of the land did not change. Cliffs still walled the coast, in some places rising sheer from the water, in others broken by a footing of coarse beach. Only flying things were to be sighted over their rocky crowns.

But by midday there was an abrupt alteration in the scene. A wide river cut through the heights and gave birth to a fan-shaped delta thickly covered with vegetation. Half hidden by the riot of growing things was a building of the dome shape Dalgard knew so well. Its windowless, doorless surface reflected the sunlight with a glassy sheen, and to casual inspection it was as untouched as it had been on the day its masters had either died within it or left it for the last time, perhaps centuries before.

"This is one way into the forbidden city," Sssuri announced. "Once they stationed guards here."

Dalgard had been about to suggest a closer inspection of the dome but that remark made him hesitate. If it had been one of the fortifications rimming in a forbidden ground, there was more than an even chance that unwary invaders, even this long after, might stumble into some trap still working automatically.

"Do we go upriver?" He left it to Sssuri, who had the traditions of his people to guide him, to make the decision.

The merman looked at the dome; it was evident from his attitude that he had no wish to examine it more closely. "They had machines which fought for them, and sometimes those machines still fight. This river is the natural entrance for an enemy. Therefore it would have been well defended."

Under the sun the green reach of the delta had a most peaceful appearance. There was a family of duck-dogs fishing from the beach, scooping their broad bills into the mud to locate water worms. And moth birds danced in the air currents overhead. Yet Dalgard was ready to agree with his companion—beware the easy way. They dipped their paddles deep and cut across the river current toward the cliffs to the north.

Two days of steady coastwise traveling brought them to a great bay. And Dalgard gasped as the full sight of the port confronting them burst into view.

Tiers of ledges had been cut and blasted in the native rock, extending from the sea back into the land in a series of giant steps. Each of them was covered with buildings, and here the ancient war had left its mark. The rock itself had been brought to a bubbling boil and sent in now-frozen rivers down that stairway in a half-dozen places, overwhelming all structures in its path, and leaving crystallized streams to reflect the sun blindingly.

"So this is your secret city!"

But Sssuri shook his round head. "This is but the sea entrance to the country," he corrected. "Here struck the day of fire, and we need not fear the machines which doubtless lie in wait elsewhere."

They beached the outrigger and hid it in the shell of one of the ruined buildings on the lowest level. Dalgard sent out a questing thought, hoping to contact a hopper or even a duck-dog. But seemingly the ruins were bare of animal life, as was true in most of the other towns and cities he had explored in the past. The fauna of Astra was shy of any holding built by Those Others, no matter how long it may have been left to the wind, and cleansing rain.

With difficulty and detours to avoid the rivers of once-molten rock, they made their way slowly from ledge to ledge up that giant's staircase, not stopping to explore any of the buildings as they passed. There was a taint of alien age about the city which repelled Dalgard, and he was eager to get out of it into the clean countryside once more. Sssuri sped on silent feet, his shoulders hunched, his distaste for the structures to be read in every line of his supple body.

When they reached the top, Dalgard turned to gaze down to the restless sea. What a prospect! Perhaps Those Others had built thus for reasons of defense, but surely they, too, must have paused now and then to be proud of such a feat. It was the most impressive site he had yet seen, and his report of it would be a worthy addition to the Homeport records.

A road ran straight from the top of the stair, stabbing inland without taking any notice of the difficulties of the terrain, after the usual arrogant manner of the alien engineers. But Sssuri did not follow it. Instead he struck off to the left, avoiding that easy path, choosing to cross through tangles which had once been gardens or through open fields.

They were well out of the sight of the city before they flushed their first hopper, a full-grown adult with oddly pale fur. Instead of displaying the usual fearless interest in strangers, the animal took one swift look at them and fled as if a snake-devil had snorted at its thumping heels. And Dalgard received a sharp impression of terror, as if the hopper saw in him some frightening menace.

"What—?" Honestly astounded, he looked to Sssuri for enlightenment.

The hoppers could be pests. They stole any small bright object which aroused their interest. But they could also be persuaded to trade, and they usually had no fear of either colonist or merman.

Sssuri's furred face might not convey much emotion, but by all the signs Dalgard could read he knew that the merman was as startled as he by the strange behavior of the grass dweller.

"He is afraid of those who walk erect as we do," he made answer.

Those who walk erect—Dalgard was quick to interpret that.

He knew that Those Others were biped, quasi-human in form, closer in physical appearance to the colonists than to the mermen. And since none of Dalgard's people had penetrated this far to the north, nor had the mermen invaded this taboo territory until Sssuri had agreed to come, that left only the aliens. Those strange people whom the colonists feared without knowing why they feared them, whom the mermen hated with a hatred which had not lessened with the years of freedom. The faint rumor carried by the migrating runners must be true, for here was a hopper afraid of bipeds. And it must have been recently provided with a reason for such fear, since hoppers' memories were very short and such terror would have faded from its mind in a matter of weeks.

Sssuri halted in a patch of grass which reached to his waist belt. "It is best to wait until the hours of dark."

But Dalgard could not agree. "Better for you with your night sight," he objected, "but I do not have your eyes in my head."

Sssuri had to admit the justice of that. He could travel under the moonless sky as sure-footed as under broad sunlight. But to guide a blundering Dalgard through unknown country was not practical. However, they could take to cover and that they did as speedily as possible, using a zigzag tactic which delayed their advance but took them from one bit of protecting brush or grove of trees to the next, keeping to the fields well away from the road.

They camped that night without fire in a pocket near a spring. And while Dalgard was alert to all about them, he knew that Sssuri was mind questing in a far wider circle, trying to contact a hopper, a runner, any animal that could answer in part the inquiries they had. When Dalgard could no longer hold open weary eyes, his last waking memory was that of his companion sitting statue-still, his spear across his knees, his head leaning a trifle forward as if what he listened to was as vocal as the hum of night insects.

When the colony scout roused in the morning, his companion was stretched full length on the other side of the spring, but his head came up as Dalgard moved.

"We may go forward without fear," he shaped the assurance. "What has troubled this land has gone."

"A long time ago?"

Dalgard was not surprised at Sssuri's negative answer. "Within days they have been here. But they have gone once more. It will be wise for us to learn what they wanted here."

"Have they come to establish a base here once more?" Dalgard brought into the open the one threat which had hung over his own clan since they first learned that a few of Those Others still lived—even if overseas.

"If that is their plan, they have not yet done it." Sssuri rolled over on his back and stretched. He had lost that tenseness of a hound in leash which had marked him the night before. "This was one of their secret places, holding much of their knowledge. They may return here on quest for that learning."

All at once Dalgard was conscious of a sense of urgency. Suppose that what Sssuri suggested was the truth, that Those Others were attempting to recover the skills which had brought on the devastating war that had turned this whole eastern continent into a wilderness? Equipped with even the crumbs of such discoveries, they would be enemies against which the Terran colonists could not hope to stand. The few weapons their outlaw ancestors had brought with them on their desperate flight to the stars were long since useless, and they had had no way of duplicating them. Since childhood Dalgard had seen no arms except the bows and the sword-knives carried by all venturing away from Homeport. And what use would a bow or a foot or two of sharpened metal be against things which could kill from a distance or turn rock itself into a flowing, molten river?

He was impatient to move on, to reach this city of forgotten knowledge which Sssuri was sure lay before them. Perhaps the colonists could draw upon what was stored there as well as Those Others could.

Then he remembered—not only remembered but was corrected by Sssuri. "Think not of taking their weapons into your hands." Sssuri did not look up as he gave that warning. "Long ago your fathers' fathers knew that the knowledge of Those Others was not for their taking."

A dimly remembered story, a warning impressed upon him during his first guided trips into the ruins near Homeport flashed into Dalgard's mind. Yes, he knew that some things had been forbidden to his kind. For one, it was best not to examine too closely the bands of color patterns which served Those Others as a means of written record. Tapes of the aliens' records had been found and stored at Homeport. But not one of the colonists had ventured to try to break the color code and learn what lay locked in those bands. Once long ago such an experiment had led to the brink of disaster, and such delvings were now considered too dangerous to be allowed.

But there was no harm in visiting this city, and certainly he must make some report to the Council about what might be taking place here, especially if Those Others were in residence or visited the site.

Sssuri still kept to the fields, avoiding the highway, until mid-morning, and then he made an abrupt turn and brought them out on the soil-drifted surface of the road. The land here was seemingly deserted. No moth birds performed their air ballets overhead, and they did not see a single hopper. That is, they did not until the road dipped before them and they started down into a cupped hollow filled with buildings. The river, whose delta they had earlier seen, made a half loop about the city, lacing it in. And here were no signs of the warfare which had ruined the port.

But in the middle of the road lay a bloody bunch of fur and splintered bone, insects busy about it. Sssuri used the point of his spear to straighten out the small corpse, displaying its headlessness. And before they reached the outer buildings of the city they found four more hoppers all mangled.

"Not a snake-devil," Dalgard deduced. As far as he knew only the huge reptiles or their smaller flying-dragon cousins preyed upon animals. But a snake-devil would have left no remains of anything as small as a hopper, one mouthful which could not satisfy its gnawing hunger. And a flying dragon would have picked the bones clean.

"Them!" Sssuri's reply was clipped. "They hunt for sport."

Dalgard felt a little sick. To his mind, hoppers were to be treated with friendship. Only against the snake-devils and the flying dragons were the colonists ever at war. No wonder that hopper had run from them back on the plain during yesterday's journey!

The buildings before them were not the rounded domes of the isolated farms, but a series of upward-pointing shafts. They walked through a tall gap which must have supported a now-disappeared barrier gate, and their passing was signaled by a whispering sound as they shuffled through the loose sand and soil drifted there in a miniature dune.

This city was in a better state of preservation than any Dalgard had previously visited. But he had no desire to enter any of the gaping doorways. It was as if the city rejected him and his kind, as if to the past that brooded here he was no more than a curious hopper or a fluttering, short-lived moth bird.

"Old—old and with wisdom hidden in it—" he caught the trail of thought from Sssuri. And he was certain that the merman was no more at ease here than he himself was.

As the street they followed brought them into an open space surrounded by more imposing buildings, they made another discovery which blotted out all thoughts of forbidden knowledge and awakened them to a more normal and everyday danger.

A fountain, which no longer played but gave birth to a crooked stream of water, was in the center. And in the muddy verge of the stream, pressed deep, was the fresh track of a snake-devil. Almost full grown, Dalgard estimated, measuring the print with his fingers. Sssuri pivoted slowly, studying the circle of buildings about them.

"An hour—maybe two—" Dalgard gave a hunter's verdict on the age of the print. He, too, eyed those buildings. To meet a snake-devil in the open was one thing, to play hide-and-seek with the cunning monster in a warren such as this was something else again. He hoped that the reptile had been heading for the open, but he doubted it. This mass of buildings would provide just the type of shelter which would appeal to it for a lair. And snake-devils did not den alone!

"Try by the river," Sssuri gave advice. Like Dalgard, he accepted the necessity of the chase. No intelligent creature ever lost the chance to kill a snake-devil when fortune offered it. And he and the scout had hunted together on such trails before. Now they slipped into familiar roles from long practice.

They took a route which should lead them to the river, and within a matter of yards, came across evidence proving that the merman had guessed correctly; a second claw print was pressed deep in a patch of drifted soil.

Here the buildings were of a new type, windowless, perhaps storehouses. But what pleased Dalgard most was the fact that most of them showed tightly closed doors. There was no chance for their prey to lurk in wait.

"We should smell it." Sssuri picked that worry out of the scout's mind and had a ready answer for it.

Sure—they should smell the lair; nothing could cloak the horrible odor of a snake-devil's home. Dalgard sniffed vigorously as he padded along. Though odd smells clung to the strange buildings none of them were actively obnoxious—yet.

"River—"

There was the river at the end of the way they had been following, a way which ended in a wharf built out over the oily flow of water. Blank walls were on either side. If the snake-devil had come this way, he had found no hiding place.

"Across the river—"

Dalgard gave a resigned grunt. For some reason he disliked the thought of swimming that stream, of having his skin laved by the turgid water with its brown sheen.

"There is no need to swim."

Dalgard's gaze followed Sssuri's pointing finger. But what he saw bobbing up and down, pulled a little downstream by the current, did not particularly reassure him. It was manifestly a boat, but the form was as alien as the city around them.