THEIR ATTEMPTS to explore on foot were frustrated by the mounds of debris and danger from falling rubble. Cully jumped to safety from the top of a mound which caved in under his weight, and so escaped a dangerous slide into one of the pits. Those pits were everywhere, dug so deeply into the foundations of the city that the Terrans, huddling on the rims, could look down past several underground levels to a darkness uncut by the sun.

A little shaken by the engineer’s narrow escape, they retired to the sled and made an unappetizing meal on concentrates.

“No birds,” Dard suddenly realized that fact. Nothing alive.”

“Unhuh.” Santee dug his heel into the grass and earth.

“No bugs either. And there’re enough of them back in the valley!”

“No birds, no insects,” Kimber said slowly. “The place is dead. I don’t know how the rest of you feel, but I’ve had just about enough.”

They did agree with that. The brooding stillness, broken only when debris crashed or rolled, rasped their nerves.

Dard swallowed his last bite of concentrate and turned to the pilot.

“Do we have any microfilm we can use?”

“For what-a lot of broken buildings?” Cully wanted to know.

“I’d like one of those bands of color around that doorway,” Dard answered. His idea that the bands had a meaning was perhaps silly but he could not push it away.

“All right, kid.” Kimber unpacked the small recorder and focused it on a place where the sun was strong. “No pattern I can see. But, it just might mean something at that.”

That was the only picture they took when on the ground. But once again in the air Cully ran the machine for a bird’s-eye view of as much of the ruined area as could be recorded.

They were approaching the outer reaches of the city to the east when Santee gave an exclamation and touched Kimber’s arm. They were over a street less cumbered with rubble than any they had yet crossed, and there was a flicker of movement there.

As the sled coasted down they disturbed a pack of grayish, four-footed things that streaked away into the ruins leaving their meal behind them on the blood-smeared pavement.

“Whew!” Cully coughed and Dard gagged at the stench the wind carried in their direction. They left the sled to gather around the tangle of stripped bones and rotting flesh.

“That wasn’t killed today,” Kimber observed unnecessarily.

Dard rounded the stained area. The dead thing had been large, perhaps the size of a Terran draft horse, and the skeleton-tumbled as the bones now were-suggested that it was four-footed and hooved. But that skull, to which ragged and blood-clotted hair still dung, was what he had moved to see. He had been right-two horns sprouted above the eye sockets. This was the horned horse of the game set!

“A duocorn?” mused the pilot.

“A what?” Santee wanted to know.

“There was a fabled animal mentioned in some of the old books on Terra. Had a single horn in the middle of the forehead, but the rest was all horse. Well, here’s a horse with two horns-a duocorn instead of a unicorn. But those things we saw feeding here-they were pretty small to bring down an animal of this size.”

“Unless they carry a burper, they didn’t!” Dard, in spite of the odor, leaned down to inspect that stretch of spine beyond the loose skull. A section of vertebra had been smashed just as if a giant vise had been applied to the nape of the duocorn’s neck!

“Crushed!” Kimber agreed. “But whatever could do that?”

Cully studied the body. “Mighty big for a horse.”

“There were breeds on earth which were seventeen to twenty hands high at the shoulder and weighed close to a ton,” returned Kimber. “This fellow must have been about that size.”

“And what is big enough to crunch through a spine supporting a ton of meat?” Santee wanted to know. He went back to the sled and picked up the rifle.

Dard back-trailed from the evil-smelling bones. Several paces farther on he discovered what he was looking for, marks which proved that the body had been dragged and worried for almost half of a city block. And also, plain to read in a drift of soil across the street, prints. The marks cut deeply by the hooves of the duocorn were half blotted out in places by another spoor-three long-clawed toes, with faint scuffed spaces between, as if they were united by a webbed membrane. Dard went down on one knee and flexed his own hand over the clearest of those prints. With his fingers spread to the fullest extent he could just span it.

“Looks like a chicken track.” Santee had come up behind him.

“More likely a reptile. I’ve seen a field lizard leave a spoor such as this-except for the size.”

“Another dragon-large size?” Cully suggested.

Dard shook his head as he got to his feet and started along that back trail. “This one runs, not flies. But I’m sure it’s a nasty customer.”

There was a scuttling to their left. Santee whirled, rifle ready. A small stone rolled from the top of the nearest pile of rubbish and thudded home against the yellow teeth of the skull:

“Somebody’s getting impatient over an interrupted dinner.” Cully ended with a laugh which sounded unnaturally loud in those surroundings.

Kimber went back to the sled. “We might as well let him-or her-or it-come back to the table. There are,” he glanced around at the ruins, “altogether too many good lurking places here. I’ll feel safer out in open country where I can see any lizard that big before it sees me!”

But when they were air borne Kimber did not turn inland, instead he followed the curve of the bay on to the northwest. The ruins beneath them dwindled to isolated houses-domed or towered-in better repair than those situated in the heart of the city. Beneath them now were brilliant patches of flowers long since returned to the wild. Little streams made graceful curves through what Dard was sure had been pleasure gardens. Fairy towers, which appeared too delicate to withstand the pull of the planet’s gravity, pointed useless fingers up at the cruising sled.

Once they flew for almost half a mile above a palace. But here again a curdled crystalline blotch cut the building in two. None of what they saw gave them any desire to descend and explore. Here the trees grew too high, there were too many shadows. The tangled pleasure gardens and wild grounds were good lurking places for terror to stalk the unwary.

The broken city faded into the green of the rolling country and the aquamarine of the sea. Fewer and fewer domed houses broke the green-and those were probably farms. Here were birds as if the haunted horror of the city was gone. The seashore curved again but Kimber did not follow it west. He veered to the east, to cross fields of which the old regular patterns were marked by bushy hedgerows. It was in one of these that they sighted the first living duocorns, four adults and two colts, but all four well under the size of the monster whose skeleton had attracted their attention in the city.

These animals were uniform in color, showing none of the variations in marking possessed by Terran horses. Their coats were a slaty blue-gray, their unkempt manes and tails black, and their bellies and the under portions of their legs silver. The horns were silver with the real sheen of the precious metal.

As the sled droned over them, the largest flung up its head to issue a trumpeting scream. Then, herding its companions before it, it settled into a rocking gallop up the sloping field to the hedge at the far side beyond which was a grove of trees. With graceful ease all of the fleeing animals leaped the hedge and disappeared under those trees, nor did they come out on the other side of the grove.

“Good runners,” Cully gave credit. “Do you suppose they were always wild-or the descendants of domestic stock? Bet Harmon’d like to have a couple of them. He was pretty fed up when he found we couldn’t bring those two colts he had picked out.”

“The big one was a fighter! D’yuh see him shake them horns?” demanded Santee. “I wouldn’t want him to catch me out in the open walkin’.”

“Odd.” Dard had been watching the far end of the grove and was now puzzled. “You’d think they’d keep on running. But they’re staying in there.”

“Under cover. Safe from any menace from the air,” Kimber said. “Which suggests some unpleasant possibilities.”

“A large flying danger!” Dard whistled as he caught Kimber’s idea. “A thing maybe as big as this sled. But it would be too big to fly on its own power!”

“Bigger things than this have flown in Terra’s past,” the pilot reminded him. “And it may not be a living thing they fear-but a machine. Either way-we’d better watch out.”

“But those flying things were far back in our history,” protested the boy. “Could such primitive things exist along with man-or whatever built that city?”

“How can we say what may or may not have survived here? Or-if that city was destroyed by radioactive missiles- -what may have mutated? Or what may fly machines?”

Since the duocorns remained stubbornly in hiding, the sled gave up investigation and flew east, the setting sun behind them and long afternoon shadows stretching to point their path.

“Where we gonna camp?”.Santee wanted to know. “Out here somewheres?”

“I’d say yes,” Kimber said. “There’s a river over there. Might find a good place somewhere along it.”

The river was shallow and its waters were clear enough for them to be able to sight from the air the rough stones which paved its bed. An uneven fringe of water plants cloaked the shore line until climbing ground provided bluffs. The sparkle of sun on ripples flashed up from a wider expanse as the sled reached a place where the graveled bed flattened out into a round lake. The stream spattered down from heights to feed this, forming a miniature waterfall, and there was a level stretch of sand unencumbered by rocks which made a good landing for the sled.

Cully stretched and grinned. “Good enough. You know how to pick ’em, Sim. Even a cave to sleep in!”

The space he pointed to was not a real cave, rather a semiprotected hollow beneath an overhang of rock. But it gave them a vague sense of security when they unrolled their sleeping bags against its back wall.

This was the first night Dard had spent in the open under a moonless sky and lie found the darkness discomforting-though stars made new crystal patterns across the heavens. They had a fire of river drift, but beyond that the darkness was thick enough to be smooth between thumb and forefinger.

The fire had died down to gleaming coals when Dard was shocked awake by a howling wail. The sound was repeated, to be either echoed or answered from down river. Above the rumble of the fall he was sure he caught the clink of disturbed gravel. Another ear-splitting shriek made his heart jump as Kimber flashed on the beam of a pocket torch without moving from beside him.

Pinned in that beam hunched a weird biped. About four feet tall, its body was completely covered with fine silky hair which arose in a fluff along its back and limbs, roughened by its astonished fright. The face was three-quarters eyes, round, staring, with no discernible lids. There was no apparent nose above an animal’s sharply fanged muzzle. Four-digit hands went up to shield those eyes and the thing gave a moan which arose to a howl. But it made no attempt to flee, as if the strange light held it prisoner.

“Monkey!” that was Santee. “A night runnin’ monkey!

Into that beam from the torch, insects began to gather-great feathery-winged moth things, some as large as birds. And, at their appearance, the night howler came to life. With a feline’s lithe grace it leaped and captured two of the moths and then scurried into the darkness where a low snarl suggested that it was now disputing possession of these prizes with another. Kimber held the torch steady and the moths came in, a drifting cloud, coasting along that ray toward the explorers. Round eyeballs of phosphorescence glittered just on the border of that light. And furry paws clawed through it at the flying things. Triumphant squeaks heralded captures and the howling arose in a triumphant chorus as if others were being summoned to this lucky hunting. Kimber snapped off the light just before the first wave of moths reached the Terrans.

The whisper of wings was drowned out by several shrill cries. But when the light was not turned on again the four heard the rattle of gravel and a fading wailing as the"monkeys” withdrew down river.

“Show’s over for this night-I hope,” Cully grunted sleepily. “Bet some wise guy could make a fortune selling torches to those boys as moth lures.”

Dard allowed his head to drop back on the padded end of the sleeping bag. Suppose those “monkeys” were intelligent enough to enable the Terrans to establish trade relations. Could one make contact with them? To the human eye their manlike stance and the way they used their hands made them appear more approachable than any other native creatures of this world which the Terrans had so far sighted. Surely these creatures had not built the city. But they walked erect and had been quick enough to evaluate the use of light for attracting their food supply. If they were wholly night creatures, as their large eyes and ease in traveling through the dark suggested, would the Terrans ever see them again?

Dard was still puzzling that out when he slipped into a dream in which he again stood before the ruined building within the city and studied those baffling lines of color. But this time those bands held a meaning, and he had almost grasped it when he heard a sound behind him. Not daring to turn his head-for he knew that death sniffed his trail-he began to run with dragging, leaden feet. And, behind him, death pounded relentlessly. With bursting lungs he turned the corner into another cluttered, half-blocked street and saw before him blood and bones from which gray things ran. He slipped, went down… He awoke, his heart pounding wildly, his body slippery with a dank, chill sweat. It was gray light. He could see the moving water, the remains of the previous night’s fire. Stealthily he wriggled out of his sleeping bag and crawled in to the open.

Then he went to the water and splashed it over head and forearms, until its clear chill washed out of him the fear the nightmare had left. Gasping a little from the chill he tramped along to the rising cliffs beside the falls.

Vines ran down the shiny black of this stone, clinging to its uneven surface with tiny sucker feet. The lianas themselves were a gray-white and bare of leaves except for a few which grew in tight bunches near the top of the cliff. Clusters of ropy creepers dangled in a limp fringe-along each main stem.

In a pocket formed by the crossing of several lianas he sighted a find. Surely that brighter green marked one of the perfume plants Trude Harmon wanted! The triangular leaves, glossy and colorful against such a drab background, bobbed from scarlet stems. And there were seed pods also! They hung, red and yellow, pulled down by the weight of their contents, within his reach. He snapped off three and stretched to reach a fourth.

It was just then he caught sight of the twitching close to the ground, where something struggled hopelessly. Two of the creepers, about the size of his little finger, were holding in a throttling grip the writhing body of a hopper. The small animal’s eyes protruded agonizingly and a bloody froth ringed its gasping mouth. Dard drew his knife and slashed at the white cords. But the steel did not cut through them. It rebounded as if he had tried to sever rubber with a dull edge. Before he could raise it for a second blow, a larger creeper flicked out and encircled his wrist, pulling him off balance against the cliff. With lightning speed the ropy fringe dangling there came to life, those near enough whipping over his body, those too far away straining toward the struggle until they were stretched in straight lines. And, as each tie fell about him, he discovered that it was equipped with small thorns which tore his skin in red-hot torment. He shouted and fought, but all his struggles seemed to carry him closer to other suckers and they were fast winding him helpless when he heard the excited cries of the others and saw them racing for him.

Before they were close enough to help he was able to tear his knife arm free, to slash and score the mass of waving tendrils which enclosed him. Then he paused-the things were failing away of their own accord. Within another minute the last and largest sullenly relinquished its hold.

“What happened?” yelled Santee. “What did you do to make those things let go?”

Wherever the plants had met his flesh they had left their brand in pin-point dots of oozing blood which trickled down his arms, throat and one cheek. But those lianas which had fallen away from him-they were turning black, shriveling, rotting away in pieces! The thing had tasted his blood and it was poisoned!

“Poisoned! I poisoned it!”

“Be glad that you did,” snapped Kimber. “You’re in luck. These weren’t!” He kicked up the gravel below the vines with the toe of his boot and plowed up brittle bones and small skulls.

The pilot as he treated Dard’s slight wounds was emphatic:

“Hereafter we stay together. It worked out all right this time. But again it might not. Stick together and distrust everything unless you have already seen it in action!”

But they were all together and apparently in no danger when disaster struck them a back-handed blow that same day. They had been using the sleepy stream as a guide back into a range of hills and by midmorning had sighted in the northeast what could only be a chain of mountains, purple-blue against the sky. These ran from north to south as far as those in the sled could see.

Perhaps if the Terrans had not been so intent upon those distant peaks they might have seen something below which would have warned them. Probably not. Man, when he goes to war, displays the deepest depths of cunning.

Their first intimation of danger arrived simultaneously with the blow that smashed them out of the sky. A sharp burst of sound and the sled bucked-as if batted by a giant club. The craft fluttered into a falling twirl while Kimber fought the controls, trying to pull out of the spin. If the passengers had not been strapped in they would have plunged earthward in the first three seconds of that wild descent.

While Dard was trying to understand what had happened a burst of brilliant light temporarily blinded him. More sound, bracketing them, and someone cried out in pain. Then he knew that they were failing out of control, and by some instinct he flung up his arms to shield his head just before they struck and he blacked out.

He couldn’t have been unconscious long, because when he raised his head Cully was still dazedly fumbling to flee himself from the safety straps. Dard spat to clear a full month and saw a blob of blood and a tooth strike the ground. He loosened the belt and lurched out of the sled after Cully. In front Santee bent over a limp Kimber on whose face blood trickled from a cut just below the hair line.

“What happened?” Dard wiped his chin and took away a bloody hand. His lips hurt and his jaw ached.

Kimber’s dark eyes opened and stared up at them bemusedly. Then comprehension came back and he demanded:

“Who shot us down?”

Santee had his rifle in his hands.

“That’s what I’m gonna see, right now!’

Before the rest could protest, he darted away, back down the valley where they had landed, zigzagging into cover as he neared its mouth. There was a final boom of an exploding shell from that direction and then silence.

Dard and Cully got Kimber free of the sled. The pilot’s right arm was bleeding from a ragged wound near the shoulder. They broke open the medical kit and the engineer went competently to work so that Dard had nothing to do. When Kimber was stretched out on a bedroll Cully returned to examine the sled itself. He took up the cover of the motor and squirmed half into the space which enclosed it, ordering Dard to hold the torch for him. When he crawled back his face was very sober.

“How bad?” asked Kimber. There was more color in his dark face and be levered himself up on an elbow.

“Not the worst-but about as near to that as we can get.” Cully was interrupted by a shout from the trees where Santee had disappeared.

The big man returned walking in the open, his rifle cradled in the crook of his arm-as if they had nothing to fear.

“Fellas, this here’s plain crazy! There’s a nest of guns down there all hidden away. Little stuff-light field pieces. But there’s not a livin’ critter in the place. Them there guns fired at us their ownselves!”

“A robot control triggered when we flew over a certain point!” exploded Cully. “Some kind of radar, I’ll bet. Rogan ought to be here.”

“First,” Kimber reminded him grimly, “we’ve got to get back to tell him about them.”

A broken sled with which to cross several hundred miles of unknown country. They were going to have quite a hike, thought Dard. But he did not comment upon that aloud.