The sun was high when they left the forest and stood at last before the mountain walls of Lys. Ahead of them the ground rose steeply to the sky in waves of barren rock. Here the river came to an end as spectacular as its beginning, for the ground opened in its path and it sank roaring from sight. Alvin wondered what happened to it, and through what subterranean caves it traveled before it emerged again into the light of day. Perhaps the lost oceans of Earth still existed, far down in the eternal darkness, and this ancient river still felt the call that drew it to the sea.
For a moment Hilvar stood looking at the whirlpool and the broken land beyond. Then he pointed to a gap in the hills. «Shalmirane lies in that direction,» he said confidently. Alvin did not ask how he knew; he assumed that Hilvar’s mind had made brief contact with that of a friend many miles away, and the information he needed had been silently passed to him.
It did not take long to reach the gap, and when they had passed through it they found themselves facing a curious plateau with gently sloping sides. Alvin felt no tiredness now, and no fear-only a taut expectancy and a sense of approaching adventure. What he would discover, he had no conception. That he would discover something he did not doubt at all.
As they approached the summit, the nature of the ground altered abruptly. The lower slopes had consisted of porous, volcanic stone, piled here and there in great mounds of slag. Now the surface turned suddenly to hard, glassy sheets, smooth and treacherous, as if the rock had once rump molten rivers down the mountain.
The rim of the plateau was almost at their feet. Hilvar reached it first, and a few seconds later Alvin overtook him and stood speechless at his side. For they stood on the edge, not of the plateau they had expected, but of a giant bowl half a mile deep and three miles in diameter. Ahead of them the ground plunged steeply downward, slowly leveling out at the bottom of the valley and rising again, more and more steeply, to the opposite rim. The lowest part of the bowl was occupied by a circular lake, the surface of which trembled continually, as if agitated by incessant waves.
Although it lay in the full glare of the sun, the whole of that great depression was ebon black. What material formed the crater, Alvin and Hilvar could not even guess, but it was black as the rock of a world that had never known a sun. Nor was that all, for lying beneath their feet and ringing the entire crater was a seamless band of metal, some hundred feet wide, tarnished by immeasurable age but still showing no slightest sign of corrosion.
As their eyes grew accustomed to the unearthly scene, Alvin and Hilvar realized that the blackness of the bowl was not as absolute as they had thought. Here and there, so fugitive that they could only see them indirectly, tiny explosions of light were flickering in the ebon walls. They came at random, vanishing as soon as they were born, like the reflections of stars on a broken sea.
«It’s wonderful!» gasped Alvin. «But what is it?»
«It looks like a reflector of some kind.»
«But it’s so black!»
«Only to our eyes, remember. We do not know what radiations they used.»
But surely there must be more than thisl Where is the fortress?»
Hilvar pointed to the lake.»Look carefully,» he said.
Alvin stared through the quivering roof of the lake, trying to plumb the secrets it concealed within its depths. At first he could see nothing; then, in the shallows near its edge, he made out a faint reticulation of light and shade. He was able to trace the pattern out toward the center of the lake until the deepening water hid all further details.
The dark lake had engulfed the fortress. Down there lay the ruins of once mighty buildings, overthrown by time. Yet not all of them had been submerged, for on the far side of the crater Alvin now noticed piles of jumbled stones, and great blocks that must once have formed part of massive walls. The waters lapped around them, but had not yet risen far enough to complete their victory.
«We’ll go around the lake,» said Hilvar, speaking softly as if the majestic desolation had struck awe into his soul. «Perhaps we may find something in those ruins over there.»
For the first few hundred yards the crater walls were so steep and smooth that it was difficult to stand upright, but after a while they reached the gentler slopes and could walk without difficulty. Near the border of the lake the smooth ebony of the surface was concealed by a thin layer of soil, which the winds of Lys must have brought here through the ages.
A quarter of a mile away, titanic blocks of stone were piled one upon the other, like the discarded toys of an infant giant. Here, a section of a massive wall was still recognizable; there, two careen obelisks marked what had once been a mighty entrance. Everywhere grew mosses and creeping plants, and tiny stunted trees. Even the wind was hushed.
So Alvin and Hilvar came to the ruins of Shalmirane. Against those walls, and against the energies they had housed, forces that could shatter a world to dust had fumed and thundered and been utterly defeated. Once these peaceful skies had blazed with fires torn from the hearts of suns, and the mountains of Lys must have quailed like living things beneath the fury of their masters.
No one had ever captured Shalmirane. But now the fortress, the impregnable fortress, had fallen at last-captured and destroyed by the patient tendrils of the ivy, the generations of blindly burrowing worms, and the slowly rising waters of the lake.
Overawed by its majesty, Alvin and Hilvar walked in silence toward the colossal wreck. They passed into the shadow of a broken wall, and entered a canyon where the mountains of stone had split asunder. Before them lay the lake, and presently they stood with the dark water lapping at their feet. Tiny waves, no more than a few inches high, broke endlessly upon the narrow shore.
Hilvar was the first to speak, and his voice held a hint of uncertainty which made Alvin glance at him in sudden surprise. «There’s something here I don’t understand,» he said slowly. «There’s no wind, so what causes these ripples? The watershould be perfectly still.»
Before Alvin could think of any reply, Hilvar dropped tothe ground, turned his head on one side and immersed his right ear in the water. Alvin wondered what he hoped to discover in such a ludicrous position; then he realized that he was listening. With some repugnance-for the rayless waters looked singularly uninviting-he followed Hilvar’s example.
The first shock of coldness lasted only for a second; when it passsed he could hear, faint but distinct, a steady, rhythmic throbbing. It was as if he could hear, from far down in the depths of the lake, the beating of a giant heart.
They shook the water from their hair and stared at each other with silent surmise. Neither liked to say what he thought that the lake was alive.
«It would be best,» said Hilvar presently, «if we searched among these ruins and kept away from the lake.»
«Do you think there’s something down there?» asked Alvin, pointing to the enigmatic ripples that were still breaking against his feet. «Could it be dangerous?»
«Nothing that possesses a mind is dangerous,» Hilvar replied. (Is that true? thought Alvin. What of the Invaders?) «I can detect no thoughts of any kind here, but I do not believe we are alone. It is very strange.»
They walked slowly back toward the ruins of the fortress, each carrying in his mind the sound of that steady, muffled pulsing. It seemed to Alvin that mystery was piling upon mystery, and that for all his efforts he was getting further and further from any understanding of the truths he sought.