The mist flew past them, then dissolved suddenly into dazzling sunlight. The scenery below them was breathtaking: deep valleys, some of them descending to the plains on either side, bare rocky slopes with knife-edged outcrops of rock, and streams of white rushing water that plunged down the mountain side and wound their way into sky- blue lakes that filled the hollows. As they floated above one of these lakes, Niall was able to see through its crystal-clear water into the brown mud in its depths.

On the lower slopes of the mountains there were patches of woodland and an occasional ruined building; one of them looked like an ancient monastery, with its bell tower still defying the elements, another like a shattered fortress. And on the coastal plain that lay between the foothills of two domelike mountains there were even the remains of a town. Whenever such a place aroused his curiosity, the spider's mind obligingly enlarged the object, so that Niall was able to study it in detail. Now he found himself looking down on a desolation of roofless houses and rubble-filled streets that left no doubt that the town had been deserted for centuries. It had once been fortified, for it was surrounded by an embankment of earth, with lookout posts built of stone. A closer view of the town revealed smoke-blackened walls and charred roof beams. On the banks of the river that flowed through its center lay the blackened remains of several boats. Nearby on the mud was an object that was unmistakably the ribcage of a man. A few feet away lay a human skull.

"Does this place have a name?"

"Men call it Cibilla, after their moon goddess."

"And who destroyed it?"

"I do not know. It happened in the days of the great war between spiders and humans, long before I was born."

"But do you people keep no records?"

"Records? I do not understand the word."

Now, at last, Niall was able to understand why the spiders were unable to offer any suggestions about the whereabouts of the kingdom of the magician. Unlike human beings, they seemed to have no legends and traditions that enshrined the knowledge of the past. It was also clear that, in this vast wilderness of rock and barren moorland, the entrance to an underground city would be virtually undetectable, even to a fleet of a million spider balloons. The underground city of Dira had remained undetected for many years, even though its goatherds and shepherds had risked discovery every day as they drove their flocks out to graze. And these misty hills, with their caves and rocky outcrops, offered far more protection than the glaring desert landscape on the shores of the great salt lake.

"Could we go higher?"

"Of course."

A moment later, they were surveying the same landscape from a height of at least ten thousand feet. Now he was able to see that the mountains stretched northward like a gigantic backbone, bending eventually to the northeast. To the left lay a wide flat plane that stretched toward the sea; in the eastern plain there were lakes and rivers, and beyond them, a lower range of mountains. From this height he was able to see that the backbone was broken in two places by wide transversal valleys, the nearest of which was about ten miles away.

Asmak pointed toward it. "That is the limit of the domain of the Death Lord. We call it the Valley of the Dead."

"Who chose that limit?"

"Why, the Death Lord himself."

"Have you ever been beyond it?"

"A few miles only. More than that would serve no purpose."

Niall could see his point; the mountains beyond the Valley of the Dead looked more bleak and forbidding than those that lay behind them to the south.

"Please take me to the boundary."

With the speed of thought, they were hovering over a wide green valley, in the center of which there was a long and narrow lake, from whose ends issued two rivers.

The Valley of the Dead must have been carved by a glacier, for its sides were steep, towering up to a height of more than a thousand feet. But what immediately drew Niall's attention was the battlemented wall that ran across the flat plain to the north of the lake.

Niall had never seen such a wall. Its color was gray-green, like that of the landscape, and it ran from the sea coast to the west for as far as the eye could see on to the eastern plain.

Its surface was smooth, unbroken by doors or other entrances. In response to Niall's curiosity, Asmak descended until they seemed to be standing on top of the wall, which was constructed of rough slabs of stone held together by some kind of cement. It was flat and about twenty feet wide, with a low parapet on either side. The southern side, Niall observed, sloped down at an angle to its base, while the northern side was a sheer drop of about eighty feet to the plain below. At regular intervals of a few hundred yards there were square towers that rose a dozen feet above the top of the wall. They were now standing within a few feet of one of these, and Niall could see that it was a kind of guardhouse, with a passageway running straight through it. Like the rest of the wall, the structure gave an impression of enormous strength.

"Who built the wall?"

"I do not know. They say it was there before the coming of the spiders. Perhaps the men who built that place."

Niall followed the spider's gaze, and for the first time noticed the buildings halfway up the great cliff. They were the same gray-blue color as the rock, which is why Niall had not noticed them immediately. There were dozens -- perhaps hundreds -- of these buildings, carved out of the solid rock face. Niall experienced a cold sensation down his spine.

"Could that be the city of the magician?"

But the spider made a gesture of dissent. "Impossible. It has always been deserted."

Niall gazed on the valley for a long time. Even the lake was awe-inspiring. Its steep sides plunged down to water whose black surface suggested enormous depths. It looked as if the earth had split asunder in some volcanic convulsion, and then filled with water.

"And where is the place where Skorbo crashed?"

"Over there, in the Gray Mountains." The spider pointed to the mountains to the north. At the same time, their perspective changed, so they were looking down on them from above. This part of the range was far more wild and precipitous than its southern reaches. Some of the peaks were like needles; others had the flat tops of volcanoes. It was a phantasmagoric landscape, quite unlike the mountain landscape in the desert of North Khaybad, where Niall had spent his childhood.

The place that Asmak was now indicating was a high plateau between two snow- covered peaks; it looked bare and inhospitable, covered with broken fragments of rock.

"Did he tell you how it happened?"

"Yes. He said that he was caught in a storm, and that the wind had made him lose control."

Niall stared at the unsheltered landscape. "What happened to the spider balloon?"

"It was torn against the rocks."

That was easy to understand; some of the rock-shards had edges that looked like razors.

"But what did he do with the balloon?"

Asmak was evidently troubled by the question. On an open plateau like this, the material of a torn spider balloon should have been clearly visible, even from a height of a thousand feet.

"I cannot recall seeing it."

As he spoke, Niall realized suddenly that this was not a real plateau that he was looking at, but merely the image of the plateau in the spider's mind. He laughed at his own forgetfulness. "I'm sorry. That was stupid of me."

But Asmak replied seriously: "You are right. None of our patrols have reported seeing the remains of the balloon. But why should Skorbo lie about it?"

"Perhaps he wasn't lying. Perhaps someone removed the balloon so we wouldn't know exactly where he crashed."

"The magician?"

"That seems possible."

The spider instantly understood the implication. "You believe that Skorbo was a traitor?"

"I believe Skorbo may have fallen into the hands of the magician. Did he ever explain what happened to him during the period after he crashed?"

"He said that he was injured, and took shelter until the storm passed. He did receive an injury to his right foreleg; I saw it."

Niall stared at the strange landscape before him -- at the massive wall that stretched as far as the eye could see in both directions, at the deserted city carved into the mountainside, and at the mist-covered mountains, with their snowy peaks, that vanished into the distance. The city still seemed to him the likeliest entrance to the kingdom of the magician. The human beings who had carved these dwellings out of the solid rock could surely burrow into the earth beneath.

But the spider, who had read Niall's thoughts, made a gesture of dissent. "Such a labor could not be completed in a thousand years."

"Even for the men who built that wall?" "A wall is a simple task. It requires only a sufficient number of slaves. But to tear out the heart of a mountain would be a labor of giants."

His mind was able to convey the full extent of his objection: an image of giant spiders (for this is how Asmak envisaged giants) burrowing into the solid rock, while an army of slaves removed the debris, carrying it to some distant place where it would not betray its origin.

Niall stared at the lower slopes of the mountain to the west. "Then where could it be? You know these mountains better than any other. Is there no place that could be the entrance to an underground kingdom?"

"I know of none."

For a long time, Niall stared at the twisted, snow-covered landscape, as if trying to wrest its secret from it. Asmak waited respectfully, prepared to answer further questions; yet Niall could sense that he felt the quest was hopeless. Niall said finally: "Thank you, commander."

As he spoke, the spider released his grip on Niall's imagination, and he found himself once more standing on the roof of the tower.

It was so dark that for a moment Niall had the strange impression that he was in some chilly dungeon. Then he felt the wind against his face, and saw stars in the blackness overhead. It came as a shock to realize that night had fallen, and that his strange mental voyage had therefore taken more than an hour. As his mind readjusted to present reality, he realized that his arm, which was resting on the parapet, had become completely dead; when he allowed it to fall to his side, it began to prickle with pins and needles. Yet the rest of his body felt normal and comfortable, and even his face, which had been exposed to the wind, was pleasantly warm.

The spider noticed his perplexity, but was too polite to ask questions. Niall explained: "The wind is cold, yet my body is warm."

The spider's response -- the equivalent of a puzzled stare -- made Niall realize that he found the comment baffling. Then the solution dawned on him. The will power of the spiders meant that they never experienced cold; when the temperature fell, they merely increased their circulation by an act of concentration. And since Niall had been sharing Asmak's consciousness, his own body had responded in the same way.

As his eyes adjusted to the darkness, Niall saw that Grel was still standing a few feet away, exactly as he had been standing an hour ago, when they had stepped out on the roof; again, he experienced wonderment at the apparently inexhaustible patience of spiders.

The night wind was already beginning to chill him. He turned and led the way back down the stairs.

The room in which the men had been working was empty; they had returned to their homes. The spider balloon on which they had been working was neatly folded in the corner of the room. And since there were no chairs, Niall went and sat down on it. He asked Grel: "Were you with us on the flight?"

For a moment the spider was puzzled; then he grasped Niall's meaning. "Yes, sire." Now he thought about it, it was obvious. There had been no "flight"; Asmak had merely told him a story, using his telepathic powers to make it seem real. And Grel had also "listened" to the story, as any normal child would.

Niall asked: "Have you ever been in a spider balloon?"

"Only once, when I was a child. My father took me on a flight over the mountains." His mind conveyed an image of the mountains to the north.

"If you were searching for the kingdom of the magician, where would you look?"

He was aware that it was a difficult question, and was surprised when the spider answered without hesitation: "At the root of the mountains."

This was an intriguing idea. Niall had been thinking of an entrance through the crater of some extinct volcano, or perhaps beneath the city carved out of the mountainside. He asked: "Why the root?"

Grel found this too difficult to explain; but his mind conveyed a picture of a river flowing into the heart of a mountain.

Niall turned to Asmak. "Do you know of any such place?"

"No, sire. But then, I have never been beyond the great wall. Shall I order our patrols to explore further north?"

Niall considered this, then shook his head. "No. It might warn our enemy that we are looking for him."

His thoughts returned to the great wall. Who had built it and why? Could it be a coincidence that it was so close to the place where Skorbo's balloon had crashed?

"Do you think that the Death Lord would know who built the wall?"

"No, sire."

"But how can you be sure?"

Asmak's reply was conveyed in a single condensed thought, whose richness and complexity would have been inexpressible in human language. What Asmak embodied, in that burst of thought-energy, was an insight into the minds of spiders: their interest in all living creatures, and their total lack of interest in such inanimate objects as walls. He made no attempt to disguise the fact that the spiders' interest in living creatures was based on their preoccupation with food, and their desire to absorb vital energy. Also implied was the admission that spiders saw the absorption of life energy as their chief means of evolution. For human beings, food is merely a chemical substance that keeps them alive; for spiders, it is the source of life itself. All this, and far more, was conveyed directly into Niall's mind, and it made him aware of the absurd poverty of human language, and of the richness of communication possible between spiders.

"But are there none among you who preserve knowledge of the past?"

"Assuredly. But only of the past of our own race."

"But perhaps the great wall is a part of your past."

"How so, my lord?"

Niall found himself wishing that he had the skill to convey his own thoughts in a single burst. "The great wall must have been built by men. Do you agree?"

"Of course."

"But which men? The human beings who lived on Earth in the age before the coming of the spiders had no use for such a wall. They had flying machines that could carry them through the air like birds, and weapons that could demolish the strongest wall into dust." "But were human beings always so skilled in technology?"

"No. The men of the ancient past built many great walls. But those walls are now ruins. This wall looks as if it has been built more recently."

The spider said with astonishment: "The human mind is amazingly subtle."

The remark made Niall aware once more of the curious limitations of the spider mind: that for all its shrewdness and sagacity, it lacked the power of logical induction.

"Who are these spiders who are versed in the history of your race?"

"The great ones of the past: Cheb the Mighty, Qisib the Wise, Greeb the Subtle, Kasib the Warrior. . ."

"But among the living?"

There was a pause, as if Asmak was searching for the right words. He said finally: "Their knowledge lives on."

"But how can I share this knowledge?"

"By entering its presence."

Niall was baffled. "But how?"

The question seemed to cause the spider some difficulty, as if he failed to grasp Niall's meaning. "You wish to do this now, sire?"

Niall said hesitantly: "If it is permitted."

Asmak answered: "You are the lord of this city. To you all things are permitted."

"Then I would like to speak with these spiders who know the history of your race."