3 hours before dawn, Private Decius awoke with a start. Why are the barracks so frightfully cold? he asked himself.  Then he remembered where he was---on the expeditionary force headed into the Forbidden Zone.

Now he heard again the noise that had awakened him from a sound sleep:  the slippery metal click of a rifle bolt being closed, opened, then closed again. Some soldier outside was cleaning his weapon. Fully awake now, he listened and heard a few apes who were obviously moving among the expeditionary vehicles.  A truck engine roared to a start, then died away in the night with a cough.  Though the force was at rest, dawn was coming, and they would soon be on the move again.

There was no movement inside Decius's troop-carrier truck, and for that he was happy.  Decius had tried to make friends with them, but the fact that he was part chimpanzee had always been a stumbling block.  They teased him because of his chimp grandmother and because, more educated than they, he was clumsy with weapons and almost totally uninterested in a soldier's life.  They constantly played tricks on him and never ceased teasing him.  Nothing bad ever happened to Decius by accident.  Of that, he was sure.

He jumped carefully from the lowered tailgate of the truck and then looked around, trying to pick out the silhouettes of the jeeps and troop carriers and tanks of the expeditionary force in the darkness.  He could make out two trucks besides his own, plus two of the heavily armored tanks----vehicles invented only months before by General Urko's pet scientists.  Each tank had a cannon and machine gun mounted on its front, and instead of tires, it had metal treads that ran on small, toothed wheels.  Because of these treads, the tanks could go almost anywhere, leaving the roadbound trucks far behind.  Decius had heard rumors that the tanks were so effective that the day of the common soldier was over---that he was soon to be replaced by equipment like these.  Of this he was very glad.

It was too dark for Decius to see much else, but he turned west and stared into the darkness at the line of low, dead-looking hills that marked the beginnings of the Forbidden Zone.  Beyond was the dead, searching openness' that contained all the fiends of Hell.

Led by Dr. Zaius but directed by General Urko, the expeditionary force had come west to the edge of the Zone last evening, arriving with just enough light for a final patrol before dark.  The final patrol had, of course, been led by Decius:  whenever there was a dangerous patrol to take out, Private Decius was chosen to lead it.

The main body of the expedition had stopped in a long, dusty line while Decius and his squad, along with a truckload of scientists, had continued down the road into the rapidly approaching dark.  Decius stood in the carrier of the truck, with its top furled on either side, his elbows on the roof of the truck's cab.  With heavy binoculars, he was searching the area ahead of them while the men behind him relaxed, eating and gambling to pass the time, and unaware of what dangers might lay before them.

Private Ligon, one of the few gorillas Decius found intelligent enough to talk to, stood beside him. They scanned the country around them, though there wasn't much to see.  The country to their right was dry, and only stunted trees and brush were scattered here and there across it.  To their left the ground climbed sharply to a long, low ridge of sun-baked rocks. And ahead of them, in the direction of the Forbidden Zone, the land was curiously obscured by a heat haze.

"I can't see anything moving," Decius told his companion.

"Maybe if you'd turn the binoculars around, Decius, and look in the small ends, you could see something," Ligon advised his friend, punching him in the shoulder and chuckling.

"What?  Oh! Well....let's have a look, then," Decius said as he adjusted the fieldglasses.

"Something's moving up there," said Ligon, pointing toward the Forbidden Zone.

Decius swung his binoculars toward the area Ligon had been scanning and saw a thin cloud of dust rising.  He watched it for a moment, but whatever was making the dust remained invisible to him.

"Just the wind, raising a bit of dust of the rocks," he said in intelligent, un-gorilla-like speech. "Nothing to worry about.  Nothing of significance."

The driver, overhearing Ligon's comment, had slowed the truck, but now he speeded up again, staying in the center of the dusty track that wasn't exactly a road.  The other truck, driven by a scientist and convoying scientists and newsapes, stayed close behind, eating the cloud of dust the first truck was kicking up.

Decius let the driver go on until they were barely a quarter-mile from the edge of the Forbidden Zone; then he signaled for the truck to turn along parallel to the Zone boundary and halt.  Just ahead were three small abandoned stone buildings, right against the demarcation line.  A small sign attached to one of the buildings warned that beyond lay the Forbidden Zone, forbidden to all non-military apes by the Books of Law.  Decius knew the buildings were religious shrines from an earlier, more primitive period in ape history.  But the warning was not primitive, and Decius shuddered when he thought about how, the next day, he would undoubtedly once more have to pass over that line into the hot desert of the Forbidden Zone.  He hoped the Underfolk would not raise their phony "Lawgiver" statue again, so strangely and so unpredictably!

He shook his head sharply, clearing such thoughts from it. Well, I'd better jump down and scout around, he told himself.  Picking up his M-16, he looked directly into the barrel of it see if it was loaded, but fortunately did not pull the trigger to make sure.

"I'm going to reconnoiter the area, Ligon.  You stay here in command of the truck, 'kay?"

Decius lowered himself from the truck carrier and made his way cautiously, like some stealthy burglar, off the side of the road, peering at each bush as if it were going to attack him.  

Suddenly, freezing Decius in his Sherlock Holmesian pose, mountainous flames sprang up around the two trucks, running back in long, yellow streaks to surround the tanks and jeeps and other carriers that had stopped some distance behind the two forward trucks and were already setting up tents for the night.  Every vehicle and all his fellow apes were outlined before Decius's horrified gaze as the fire arced upward, seeming to burn the very sky.

The ground began to shake, and yawning fissures opened in zigzag paths across the ground.  Rocking to and fro, Decius lost his balance and fell backward, squarely atop an immense round cactus!

This finally scattered any bravery Decius might have had.

"They've stabbed me!" he screamed.  "The enemy is upon us!" he yelled, bolting away from the cactus and running back toward the line of trucks and his fellow apes.  But his running path was not straight; it was a series of angles as he dodged opening and closing chasms---each, he was sure, led directly to Hell.

Decius almost made it back to the safety of his truck.  Almost, but not quite.  As he dodged a final crack in the ground, bright orange and green flames spurted from it and, panting and terror-stricken, he rushed down the road now at full tilt, hardly noticing where he was running.  Ligon and his patrol truck were left far behind!

Decius did not notice the half-inch-thick rope stretched across his path. The rope supported one end of a big, ornate tent.

He landed, rolling, almost at the feet of Dr. Zaius and General Urko.  The general pierced Decius with a look that boded nothing but contempt for the unfortunate soldier, and Decius wondered if perhaps death among the sprouting flames might not be better than the wrath of the burly Urko.

Decius was saved, however, by Dr. Zaius.

Soldiers were clustered around the tent, cowering before the flames, their weapons clutched in desperation as they sought targets.  Zaius was gazing about at the geysers of fire, awed by the sight and somewhat afraid of forces he could not understand, but unwilling to give in to those fears.

For a moment, the ground quit rocking and Zaius took advantage of the relative peace to stop forward toward the flames.  Fifteen feet from the road, he turned back towards the tent and raised his arms.

"Look at me!" he shouted in a voice that could be heard even over the roaring of the flames.  "Look at me!  There's nothing to fear!  This is a mere illusion!"

To emphasize his point, he walked straight toward a yawning chasm to his right.  As he reached it, yellow flames licked up at him and a loud groan went up from the troops huddled around the tent.  But Zaius walked through the flames, over the empty space of the chasm!

"It's an illusion!" he repeated. "It can't hurt you!"

With those last words, the flames disappeared and the cracks in the earth healed themselves.  For a moment Dr. Zaius thought he'd prevailed over whatever, or whoever was causing the illusions.  But then a new apparition appeared in the sky over the expeditionary force.

The Elder had almost made it back to the tent when a roar of thunder exploded above his head and streaks of lightning began to race across the cloudless sky.  A bolt hit the ground 20 feet from the tent, leaving behind a smoking crater 3 feet deep by 10 feet across.

For a moment, Dr. Zaius stood with his head bowed under the weight of the noise from the sky.  Then he stepped over to the edge of the tent, beside General Urko.

"Scared, Zaius?" Urko asked with a sneer.

"Of course I'm frightened," Dr. Zaius replied. "I know it's only an illusion. But whatever has the power to create such illusions perhaps also has the power to stop us---if that's its aim."

Urko began to stay something in answer to Zaius, but his words were drowned by a giant, piercing shriek that echoed across the sky, accompanied by sheets of white-hot lightning bolts.

The eyes of both apes were yanked skyward, and there, almost directly above them---wreathed in lightning---was the skull of a screaming ape.  A skull fully a hundred feet across, with bolts of electricity flashing from its eye sockets and clouds of colored fire billowing from its ears.

The skull wailed again, and fire streamed out from its mouth as it roared.  Then, as every ape in the expedition watched, the skull turned slowly, as if scanning the entire line of trucks and tents, and stopped, pointed at the tent where Zaius and Urko were standing.

"Remember the Books of Law!" the voice thundered from the sky. "Enter not the Forbidden Zone needlessly, lest your souls be sent to burn in the Lake of Fire for eternity!" And again, the piercing scream tore the sky, along with sheets of fire from the skull's mouth.

"Begone!" Dr. Zaius yelled back, stepping forward.  "You're nothing but an illusion, and you cannot hurt us!"

A sheet of fire abruptly flashed down from the skull and enveloped the old ape, but the orangutan Elder held his ground, staring defiantly up into the sky.

Suddenly, the night was silent again, the only light a rosy tint on the eastern horizon, heralding the dawn.

"That was a brave thing you did, Zaius," the general said, with grudging respect in his voice.

"Hmmph!  Not really. 'You can fool some of the apes some of the time, but you can't fool all of the apes all of the time.' And you can't fool me at all!  Not with an illusion!"

Again, Zaius walked to the side of the road, then turned and looked along the column, illuminated by the lights of the many trucks and few campfires.  "You see," he shouted to the troops. "There's nothing to worry about!"

Urko muttered under his breath, barely audible, “I’ve seen what crawls beneath the rocks... long ago, when I was just a cub—they never forget a face.”

Zaius stepped back to the tent.  "How about some supper, general?"

"I'll have the orderly bring us some. Shall we discuss our plans for the coming day, doctor?"

Zaius nodded his head and started to step into the tent but stopped suddenly.  "Who's that?" he asked.

Trying to make himself invisible, Decius eased back out of the circle of light from the tent.  General Urko looked sharply at him again, but said nothing, and Decius got quickly to his feet and set off at a trot back toward his truck.