"We'll never know. Look at these friezes. They portray women. What race do they belong to?"

  Conyn scanned them and shook her head.

  "I never saw people exactly like them. But there's the smack of the East about them--Vendhya, maybe, or Kosala."

  "Were you a queen in Kosala?" he asked, masking his keen curiosity with derision.

  "No. But I was a war chief of the Afghulis who live in the Himelian mountains above the borders of Vendhya. These people favor the Kosalans. But why should Kosalans be building a city this far to the west?"

  The figures portrayed were those of slender, olive-skinned women and men, with finely chisled, exotic features. They wore filmy robes and many delicate jeweled ornaments, and were depicted mostly in attitudes of feasting, dancing, or lovemaking.

  "Easterners, all right," grunted Conyn, "but from where I don't know. They must have lived a disgustingly peaceful life, though, or they'd have scenes of wars and fights. Let's go up those stairs."

  It was an ivory spiral that wound up from the chamber in which they were standing. They mounted three flights and came into a broad chamber on the fourth floor, which seemed to be the highest tier in the building. Skylights in the ceiling illuminated the room, in which light the fire-gems winked pallidly. Glancing through the doors they saw, except on one side, a seies of similarly lighted chambers. This other door opened upon a balustraded gallery that overhung a hall much smaller than the one they had recently explored on the lower floor.

  "Hell!" Valerian sat down disgustedly on a jade bench. "The people who deserted this city must have taken all their treasures with them. I'm tired of wandering through these bare rooms at random."

  "All these upper chambers seem to be lighted," said Conyn. "I wish we could find a window that overlooked the city. Let's have a look through that door over there."

  "You have a look," advised Valerian. "I'm gonig to sit here and rest my feet."

  Conyn disappeared through the door opposite that one opening upon the gallery, and Valerian leaned back with his hands clasped behind his head, and thrust his booted legs out in front of him. These silent rooms and halls with their gleaming green clusters of ornaments and burning crimson floors were beginning to depress him. He wished they could find their way out of the maze into which they had wandered and emerge into a street. He wondered idly what furtive, dark feet had glided over those flaming floors in past centuries, how many deeds of cruelty and mystery those wrinking ceiling-gems had blazed down upon.

  It was a faint noise that brought him out of his reflections. He was on his feet with his sword in his hand before he realized what had disturbed him. Conyn had not returned, and he knew it was not she that he had heard.

  The sound had come from somewhere beyond the door that opened on to the gallery. Soundlessly in his soft leather boots he glided through it, crept across the balcony and peered down between the heavy balustrades.

  A woman was stealing along the hall.

  The sight of a human being in this supposedly deserted city was a startling shock. Crouching down behind the stone balusters, with every nerve tingling, Valerian glared down at the stealthy figure.

  The woman in no way resembled the figures depicted on the friezes. She was slightly above middle height, very dark, though not Negroid. She was naked but for a scanty silk clout that only partly covered her muscular hips, and a leather girdle, a hand's breadth broad, about her lean waist. Her long black hair hung in lank strands about her shoulders, giving her a wild appearance. She was gaunt, but knots and cords of muscles stood out on her arms and legs, without that fleshy padding that presents a pleasing symmetry of contour. She was built with an economy that was almost repellent.

  Yet it was not so much her physical appearance as her attitude that impressed the man who watched her. She slunk along, stooped in a semi-crouch, her head turning from side to side. She grasped a widetipped blade in her right hand and he saw it shake with the intensity of the emotion that gripped her. She was afraid, trembling in the grip of some dire terror. When she turned her head he caught the blaze of wild eyes among the lank strands of black hair.

  She did not see him. On tiptoe she glided across the hall and vanished through an open door. A moment later he heard a choking cry, and then silence fell again.

  Consumed with curiosity, Valerian glided along the gallery until he came to a door above the one through which the woman had passed. It opened into another, smaller gallery that encircled a large chamber.

  This chamber was on the third floor, and its ceiling was not so high as that of the hall. It was lighted only by the fire-stones, and their weird green glow left the spaces under the balcony in shadows.

  Valerian's eyes widened. The woman he had seen was still in the chamber.

  She lay face down on a dark crimson carpet in the middle of the room. Her body was limp, her arms spread wide. Her curved sword lay near him.

  He wondered why she should lie there so motionless. Then his eyes narrowed as he stared down at the rug on which she lay. Beneath and about her the fabric showed a slightly different color, a deeper, brighter crimson.

  Shivering slightly, he crouched down closer behind the balustrade, intently scanning the shadows under the overhanging gallery. They gave up no secret.

  Suddenly another figure entered the grim drama. She was a woman similar to the first, and she came in by a door opposite that which gave upon the hall.

  Her eyes glared at the sight of the woman on the floor, and she spoke something in a staccato voice that sounded like "Chicmec!" The other did not move.

  The woman stepped quickly across the floor, bent, gripped the fallen woman's shoulder and turned her over. A choking cry escaped her as the head fell back limply, disclosing a throat that had been severed from ear to ear.

  The woman let the corpse fall back upon the blood-stained carpet, and sprang to her feet, shaking like a windblown leaf. Her face was an ashy mask of fear. But with one knee flexed for flight, she froze suddenly, became as immobile as an image, staring across the chamber with dilated eyes.

  In the shadows beneath the balcony a ghostly light began to glow and grow, a light that was not part of the fire-stone gleam. Valerian felt his hair stir as he watched it; for, dimly visible in the throbbing radiance, there floated a human skull, and it was from this skull-- human yet appallingly misshapen--that the spectral light seemed to emanate. It hung there like a disembodied head, conjured out of night and the shadows, growing more and more distinct; human, and yet not human as he knew humanity.

  The woman stood motionless, an embodiment of paralyzed horror, staring fixedly at the apparition. The thing moved out from the wall and a grotesque shadows moved with it. Slowly the shadow became visible as a man-like figure whose naked torso and limbs shone whitely, with the hue of bleached bones. The bare skull on its shoulders grinned eyelessly, in the midst of its unholy nimbus, and the woman confronting it seemed unable to take her eyes from it. She stood still, her sword dangling from nerveless fingers, on her face the expression of a woman bound by the spells of a mesmerist.

  Valerian realized that it was not fear alone that paralyzed her. Some hellish quality of that throbbing glow had robbed her of her power to think and act. He himself, safely above the scene, felt the subtle impact of a nameless emanation that was a threat to sanity.

  The horror swept toward its victim and she moved at last, but only to drop her sword and sink to her knees, covering her eyes with her hands. Dumbly she awaited the stroke of the blade that now gleamed in the apparition's hand as it reared above her like Death triumphant over mankind.

  Valerian acted according to the first impulse of his wayward nature. With one tigerish movement he was over the balustrade and dropping to the floor behind the awful shape. It wheeled at the thud of his soft boots on the floor, but even as it turned, his keen blade lashed down and a fierce exultation swept his as he felt the edge cleave solid flesh and mortal bone.

  The apparition cried out gur
glingly and went down, severed through the shoulder, breastbone and spine, and as it fell the burning skull rolled clear, revealing a lank mop of black hair and a dark face twisted in the convulsions of death. Beneath the horrific masquerade there was a human being, a woman similar to the one kneeling supinely on the floor.

  The latter looked up at the sound of the blow and the cry, and now she glared in wild-eyes amazement at the whiteskinned man who stood over the corpse with a dripping sword in his hand.

  She staggered up, yammering as if the sight had almost unseated her reason. He was amazed to realize that he understood her. She was gibbering in the Stygian tongue, though in a dialect unfamiliar to her.

  "Who are you? Whence come you? What do you in Xuchotl?" Then rushing on, without waiting for his to reply: "But you are a friend--goddess or devil, it makes no difference! You have slain the Burning Skull! It was but a woman beneath it, after all! We deemed it a demon they conjured up out of the catacombs! Listen!"

  She stopped short in her ravings and stiffened, straining her ears with painful intensity. The boy heard nothing.

  "We must hasten!" she whispered. "They are west of the Great Hall! They may be all around us here! They may be creeping upon us even now!"

  She seized his wrist in a convulsive grasp he found hard to break.

  "Whom do you mean by 'they?'" he