The rock fell to the ground. The gun paused, then resumed its calm swivel, its slow circling.

“You see,” Dorle said, “it noticed the rock, as soon as I threw it up in the air. It’s alert to anything that flies or moves above the ground level. Probably it detected us as soon as we entered the gravitational field of the planet. It probably had a bead on us from the start. We don’t have a chance. It knows all about the ship. It’s just waiting for us to take off again.”

“I understand about the rock,” Nasha said, nodding. “The gun noticed it, but not us, since we’re on the ground, not above. It’s only designed to combat objects in the sky. The ship is safe until it takes off again, then the end will come.”

“But what’s this gun for?” Tance put in. “There’s no one alive here. Everyone is dead.”

“It’s a machine,” Dorle said. “A machine that was made to do a job. And it’s doing the job. How it survived the blast I don’t know. On it goes, waiting for the enemy. Probably they came by air in some sort of projectiles.”

“The enemy,” Nasha said. “Their own race. It is hard to believe that they really bombed themselves, fired at themselves.”

“Well, it’s over with. Except right here, where we’re standing. This one gun, still alert, ready to kill. It’ll go on until it wears out.”

“And by that time we’ll be dead,” Nasha said bitterly.

“There must have been hundreds of guns like this,” Dorle murmured. “They must have been used to the sight, guns, weapons, uniforms. Probably they accepted it as a natural thing, part of their lives, like eating and sleeping. An institution, like the church and the state. Men trained to fight, to lead armies, a regular profession. Honored, respected.”

Tance was walking slowly toward the gun, peering nearsightedly up at it. “Quite complex, isn’t it? All those vanes and tubes. I suppose this is some sort of a telescopic sight.” His gloved hand touched the end of a long tube.

Instantly the gun shifted, the barrel retracting. It swung—

“Don’t move!” Dorle cried. The barrel swung past them as they stood, rigid and still. For one terrible moment it hesitated over their heads, clicking and whirring, settling into position. Then the sounds died out and the gun became silent.

Tance smiled foolishly inside his helmet. “I must have put my finger over the lens. I’ll be more careful.” He made his way up onto the circular slab, stepping gingerly behind the body of the gun. He disappeared from view.

“Where did he go?” Nasha said irritably. “He’ll get us all killed.”

“Tance, come back!” Dorle shouted. “What’s the matter with you?”

“In a minute.” There was a long silence. At last the archeologist appeared. “I think I’ve found something. Come up and I’ll show you.”

“What is it?”

“Doric, you said the gun was here to keep the enemy off. I think I know why they wanted to keep the enemy off.”

They were puzzled.

“I think I’ve found what the gun is supposed to guard. Come and give me a hand.”

“All right,” Doric said abruptly. “Let’s go.” He seized Kasha’s hand. “Come on. Let’s see what he’s found. I thought something like this might happen when I saw that the gun was—”

“Like what?” Nasha pulled her hand away. “What are you talking about? You act as if you knew what he’s found.”

“I do.” Doric smiled down at her. “Do you remember the legend that all races have, the myth of the buried treasure, and the dragon, the serpent that watches it, guards it, keeping everyone away?”

She nodded. “Well?”

Doric pointed up at the gun.

“That,” he said, “is the dragon. Come on.”

Between the three of them they managed to pull up the steel cover and lay it to one side. Doric was wet with perspiration when they finished.

“It isn’t worth it,” he grunted. He stared into the dark yawning hold. “Or is it?”

Nasha clicked on her hand lamp, shining the beam down the stairs. The steps were thick with dusk and rubble. At the bottom was a steel door.

“Come on,” Tance said excitedly. He started down the stairs. They watched him reach the door and pull hopefully on it without success. “Give a hand!”

“All right.” They came gingerly after him. Doric examined the door. It was bolted shut, locked. There was an inscription on the door but he could not read it.

“Now what?” Nasha said.

Doric took out his hand weapon. “Stand back. I can’t think of any other way.” He pressed the switch. The bottom of the door glowed red. Presently it began to crumble. Doric clicked the weapon off. “I think we can get through. Let’s try.”

The door came apart easily. In a few minutes they had carried it away in pieces and stacked the pieces on the first step. Then they went on, flashing the light ahead of them.

They were in a vault. Dust lay everywhere, on everything, inches thick. Wood crates lined the walls, huge boxes and crates, packages and containers. Tance looked around curiously, his eyes bright.

“What exactly are all these?” he murmured. “Something valuable, I would think.” He picked up a round drum and opened it. A spool fell to the floor, unwinding a black ribbon. He examined it, holding it up to the light.

“Look at this!”

They came around him. “Pictures,” Nasha said. “Tiny pictures.”

“Records of some kind.” Tance closed the spool up in the drum again. “Look, hundreds of drums.” He flashed the light around. “And those crates. Let’s open one.”

Doric was already prying at the wood. The wood had turned brittle and dry. He managed to pull a section away.

It was a picture. A boy in a blue garment, smiling pleasantly, staring ahead, young and handsome. He seemed almost alive, ready to move toward them in the light of the hand lamp. It was one of them, one of the ruined race, the race that had perished.

For a long time they stared at the picture. At last Doric replaced the board.

“All these other crates,” Nasha said. “More pictures. And these drums. What are in the boxes?”

“This is their treasure,” Tance said, almost to himself. “Here are their pictures, their records. Probably all their literature is here, their stories, their myths, their ideas about the universe.”

“And their history,” Nasha said. “We’ll be able to trace their development and find out what it was that made them become what they were.”

Doric was wandering around the vault. “Odd,” he murmured. “Even at the end, even after they had begun to fight they still knew, someplace down inside them, that their real treasure was this, their books and pictures, their myths. Even after their big cities and buildings and industries were destroyed they probably hoped to come back and find this. After everything else was gone.”

“When we get back home we can agitate for a mission to come here,” Tance said. “All this can be loaded up and taken back. We’ll be leaving about—”

He stopped.

“Yes,” Doric said dryly. “We’ll be leaving about three day-periods from now. We’ll fix the ship, then take off. Soon we’ll be home, that is, if nothing happens. Like being shot down by that—”

“Oh, stop it,” Nasha said impatiently. “Leave him alone. He’s right: all this must be taken back home, sooner or later. We’ll have to solve the problem of the gun. We have no choice.”

Doric nodded. “What’s your solution, then? As soon as we leave the ground we’ll be shot down.” His face twisted bitterly. “They’ve guarded their treasure too well. Instead of being preserved it will lie here until it rots. It serves them right.”

“How?”

“Don’t you see? This was the only way they knew, building a gun and setting it up to shoot anything that came along. They were so certain that everything was hostile, the enemy, coming to take their possessions away from them. Well, they can keep them.”

Nasha was deep in thought, her mind far away. Suddenly she gasped. “Doric,” she said. “What’s the matter with us? We have no problem. The gun is no menace at all.”