Culver was moving through one of the dim side-passages between his work zone and the bathing pits when he turned a corner and saw them. They were milling around in a wide spot in the tunnel about fifty feet ahead. He turned immediately and started back the way he'd come, wanting no part of it. But they'd seen him; the sharp command that pierced his mind a second later was proof of that. In another second it would be worse than a command. Before that could happen, he turned again, and moved toward them.

         There were four of them, two boys and two hills. He'd walked in on them just as they were getting ready to start. The kids were both from his birth group: seven cycles old, or about ten of the old years. He knew one vaguely, a boy named Wyatt from his own sleeping chamber. He didn't know the other's name, though he'd seen him around.

         The hills were average size and shape, something like nine feet tall, wide and square at their bases, tapering steadily up to where their bodies ended abruptly in smaller, slightly rounded squares. The effect was of a pyramid with its apex sheared off and its edges softened, but Culver was unable to make such a comparison, having never seen nor heard of a pyramid. One was a deep, dark green, the most common coloration. The other was the dark gray you saw fairly often, with faint undertones of something like scarlet.

         The hills stiffened, losing the trace of softness usually evident in their piled flesh. The change in the boys was less obvious, but perceptible. Their eyes went glassy and distant. Their faces slackened, and beads of sweat began to show on their foreheads.

         They'd started about ten feet apart, and they came toward each other jerkily, Wyatt turning an ankle and almost falling on his second or third step. That would hurt when he came around. The other boy reared back and swung much too early, almost overbalancing but managing to right himself and continue forward. Wyatt swung, and connected weakly, tapping the other's shoulder to no visible effect.

         The other boy grabbed at Wyatt's face, but his hill—the gray one, Culver thought—was having difficulty with its depth-perception; the boy's grubby fingers closed more than half a foot in front of Wyatt's oblivious face. Wyatt's hill was content to swing again, this time with Wyatt's left hand. This punch looked like it was meant for the other kid's chest, but Wyatt's left arm slapped against the kid's right before the fist could reach its target.

         Now they were too close for punches, though Wyatt's hill was still trying. Culver had seen two of these fights before, and both had quickly degenerated into the chaotic flurry of arms he saw now. The boys' arms swung around madly, but slowly, as if in underwater panic. Their chests bumped sporadically; one or both of the hills was still moving its boy forward, intentionally or not.

         All at once Wyatt stumbled backward. It might've been the glancing elbow to the chin Culver saw him take, or just the collapse of the hill's deteriorating balance. The hill tried to keep Wyatt upright, not as a person would, with outstretched arms and subtle twists of the body, but with a series of motions that was somehow entirely alien, despite taking place in a human form.

         Wyatt twisted his knees and hips violently to the right. The bones of his legs seemed to be straining to twist in the same manner. Watching him fall, Culver could picture a hill, somehow toppled from its wide stance, flattening the lower edge of its pyramid to prevent itself from going over. It might've worked for them; Culver had never seen one even close to losing its balance. It did nothing for Wyatt but slightly alter the trajectory of his fall.

         Culver closed his eyes just in time to avoid seeing the inevitable. The hills had no heads, so they lacked the instinct to tuck the chin against the chest, or brace the body with the arms, or in any other way protect the head in a fall. Culver had seen a man who was being walked take such a fall, in the first fight he'd witnessed. He'd dreamed about it. He didn't see Wyatt meet the floor of the tunnel, but he heard it.

         When the echoes had died, he opened his eyes. Wyatt was still, and his eyes were open, staring up at the tunnel's ceiling. The man had not been still, but had bucked and shaken like a dying snake.

         The other boy was doing some kind of grotesque victory dance, his arms held straight up above his head, his feet describing long, irregular circles on the stone floor. The gray hill had relaxed; it was the green one that was still stiff, walking the winning boy. So Culver had been wrong.

         He watched the gray hill. If it were fatigued from the fight, he would be okay. If it still felt strong, he would not be. The dance the green one was making its boy do was as much a challenge as a celebration, and if the gray one were still able to fight, Culver thought it would accept. He'd been walked before, but never made to fight.

         The green one relaxed, and a second later the hills went oozing off down the tunnel. The boy Culver didn't know was staring down at Wyatt with a blank expression, his arms still half raised. As Culver watched, the boy lowered them, and looked around. He saw Culver, and pointed to Wyatt, who was up on his knees now, staring at the hills as they moved away down the tunnel.

         “Kicked his face in for him,” the boy said.

         Culver said nothing. He didn't know the boy well enough to tell him what had actually happened. That would likely start another fight, and the boy looked able to handle himself better than the hill had. Culver might tell Wyatt, but probably not. Wyatt and the other boy would assume it had been a fight between them, their minds working frantically to invent motivations and place the specifics within a narrative that didn't include their minds and bodies being seized. Culver had done the same, automatically, when he'd been walked; it was only self-defense. He'd come close to fighting the boys who'd told him, closer still to bursting into tears. It was a horrifying thing to realize. It was a source of irrational but powerful shame.

         The boy turned, and took a few steps in the direction in which the hills had gone. He seemed to notice them for the first time. He turned on his heel and walked back the other way. He rounded a bend in the tunnel, and was gone.

         Wyatt vomited. When he'd unloaded everything, he heaved some more. Long, thick lines of dirty spit clung stubbornly to his lips. Culver stood there, not knowing why. The tunnel stank of Wyatt's vomit. Culver wanted to bathe now more than ever.

         Wyatt rose shakily, one hand against the cold tunnel wall, the other resting gingerly on the back of his head. “I slipped,” he said suddenly. Culver nodded. Wyatt was busy manufacturing the scenario. “That kid cheats. He grabbed at me.” Culver didn't deny it, but didn't agree, either. He didn't have the heart to accuse the boy of something over which he'd had no control.

         Without knowing he was going to, Culver slipped his arm under Wyatt's shoulder. The boy let himself be supported. Culver looked down the tunnel the hills had taken. They were out of sight now. He stared a little longer, then turned himself and Wyatt in the opposite direction, and moved slowly down the tunnel.

#

         Culver squirmed along the narrow passage, shoulders scraping against the rough-cut stone. He was almost too big for this work. A few more sub-cycles and he'd be transferred to a clearance team. Two or three cycles after that, he'd join the men in the real work, as a driller or a picker or a driver.

         He didn't mind mole work. Being closely surrounded on all sides by the unyielding rock gave him a sense of protection. The horror stories of boys getting trapped in fresh cuts like this one, or being caught in collapses or explosions, didn't bother him. Almost always such mishaps could be ascribed to some mistake the boy had made. In the back of his mind, Culver was aware that such explanations might be more a matter of mental self-defense than accuracy. But they were comforting, so he didn't examine them too closely.

         The only light was his handful of glow. He didn't bother smearing it on the walls as he went; there was no danger of getting lost. The billions of tiny luminescent organisms that made up the glow emitted enough of their steady, green-white light to show him the tunnel a few yards ahead.

         When he came to the abrupt end of the cut, he stopped within a few feet of the blank stone, and applied the glow in a haphazard smear. By its light, he placed the charge, pressed the button to start its timer, and began backing out of the cut. Several times his shoulders stuck, or his legs tangled themselves awkwardly. No mole run was complete without at least a few such panicky moments, and this time there were no more than usual. He was out of the cut and safely back with the others, a few hundred yards up the main tunnel, when the explosion came. It was shattering, despite the wads of cloth stuck in his ears. It came not just from the direction of the cut, but from all sides, as if Culver and the rest of the team were in the only pocket of relative calm amidst an explosion that encompassed the whole earth.

         Peter led them back to the cut, and sent Ethan, a boy one or two cycles younger than Culver, up the cut to examine the effects of the blast. The rock was hard here, and possibly it would take another blast before they could bring in the big equipment and begin digging in earnest.

         While the team milled around, Peter handed Culver the canteen, and waited while he drank his fill. Unlike some team-leaders he'd worked under, Peter was never overly protective of the water, nor did he allow himself private, covert drinks. He distributed it as needed, only holding back when the supply was low, and then always sacrificing the largest fraction from his own share.

         “I think you got it with that one,” Peter said, as he took back the canteen. He raised it to his mouth, tipped it momentarily up, lowered it almost immediately. “Got right down to the end, didn't you?”

         Culver nodded.

         “Half the kids don't even bother to go all the way through now,” Peter said. “One kid, this was two or three cycles ago, he barely went far enough to be out of sight. Must've just sat there for a while before he set the charge and came out. When the blast went off it nearly took down that whole stretch of tunnel. Fried the glow off the walls for a hundred yards. When I was a mole, you'd get the hell beaten out of you for a stunt like that.”

         Culver only realized when Peter stopped that the man had been moving slowly backward as he spoke, and that Culver had been following. Now they were directly beneath the nearest patch of glow. When Culver spoke, and saw the closeness with which Peter watched his mouth, he remembered that the man's long career as a digger had rendered him nearly deaf.

         “That's stupid,” Culver said. “You just have to go back in. Or someone does.”

         “They're scared,” Peter said. “Some kids, they just can't handle it. They should be doing something else. But the hills don't give a damn.”

         Culver nodded. When he'd first grown old enough to work, he'd hoped to join the food staff, putting him on track to become a server, then a cook's apprentice, then finally a cook. But there were far less positions in cooking, or medicine, or any of the other ancillary occupations, than in the main concern of digging.

         “To be honest,” Peter said, “I didn't like it much. Digging's okay, but the mole runs weren't my idea of a good time.” He smiled. “I got a beating or two myself.”

         “Was that...”

         “What?”

         “Was that when... I mean, did you ever see...”

         Peter's smile broke wide open, the few patches of white on his grimy teeth catching the glow. “Are you asking if I've seen the surface? How old do you think I am?”

         Peter looked well over twenty, in the old years; maybe closer to thirty. Not quite ancient, but getting there. Culver flushed, and said hurriedly, “No. I guess not.”

         “Well, sorry. I may be old, but I'm not that old.”

         Culver knew he should shut up. Still, he couldn't stop himself from going on. “I just always wondered,” he said, beginning to lower his head before remembering, and raising his face so Peter could see his lips. “I mean, what it was like.”

         “The surface. I know. I used to wonder about it too. I guess everybody does, at some point. I don't know when I stopped wondering. But I don't anymore.”

         “Some kids say it's just a shadow story, like trolls, and ghosts.”

         “Yeah. Well, it's not. We didn't always live like this. The surface was real.”

         “How do you know?”

         “Well, I never met anyone who actually saw it. Or anyone who met anyone who did. But the men tell the boys, and when they grow up they tell more. Like I'm doing now, I guess.”

         Culver was thinking the same could be said of the shadow stories. They were passed down in the same way, and that didn't make them true. In fact, he was about seventy percent sure they weren't true. But he knew better than to say it out loud.

         Peter may've read the skepticism on his face, though. “Plus,” he said, “if you ever want to know for sure, just ask a hill. They'll be glad to tell you.”

         Culver cringed at the thought. He'd been sent on that kind of errand before, tasked with speaking to—or anyway, communicating with—a hill, to get access to some needed tool, or a resupply of food or water. This was the worst job of all, so bad that teams didn't keep regular messengers, but rotated the job among all the men and boys; unless, of course, someone needed to be punished, for slacking off, or stealing food, or, say, annoying the team-leader with stupid questions.

         “What was it like?” Was that another stupid question? It had to be asked, regardless.

         “You wouldn't believe me,” Peter said. “I hardly believe it myself. Come to think of it, I don't know if I even do. But I'll tell you what they say. They say the surface had more light than all the glow in all the tunnels in the earth. And that was the dark half. Half the surface was dark, and half was light.”

         Culver felt his brow wrinkle at the absurdity. “Why?”

         Peter shrugged. “Why's stone hard? Why're people soft? Who knows? That's not even the strangest part.”

         Culver thought Peter would speak next about the one thing everyone knew about the surface, that it was supposed to have no ceiling, but just go up and up forever. Culver had often tried to picture this, imagining the highest ceiling of the largest chamber he'd ever been in, then pushing that up even higher, as high as his mind could imagine. The higher it went, the dizzier he got, and the less believable he found the whole exercise. He'd never come close to eliminating the ceiling entirely.

         But Peter was talking about something else. “There was moss everywhere there, or things that look like moss. Imagine a clump as tall as a man, as tall as a hill, taller than two hills.”

         Culver hoped he wasn't actually meant to imagine such a thing.

         “Moss covered all the ground, sprouted up into the sky. And things lived everywhere, not just moss but animals, animals you've never dreamed of.”

         Culver tried to picture the blind white rats and snakes and salamanders that were his only conception of animals, swarming all over this strange, bright, moss-covered world.

         “Animals with bodies the size of a hill, and necks twice as high again. Noses longer than a whole man. Some of them could run faster than a truck on a straightaway. Some of them could move through the air without touching the ground, just by swinging their arms.”

         Culver's eyes bulged.

         “Or swim,” Peter said. “There were lakes that went on and on forever, farther than you could swim in a whole cycle. And animals lived in them, animals so small you couldn't see them, so big they could swallow you whole without even knowing it. There was water everywhere, so much it sometimes fell from the ceiling, or the place where the ceiling would be. And not just drip, drip, drip. A million drips, all at the same time. Drip-drip-drip-drip-drip, for hours.”

         Culver had given up trying to picture it, which somehow made picturing it possible. His mind made no effort to make sense of Peter's fanciful images, instead allowing them to arrange themselves as they would. The picture was strange indeed.

         “And do you know who it all belonged to? Who were the kings of all the surface?”

         Culver knew somehow his answer was wrong, but he could think of nothing else to say. “The hills?”

         Peter's smile shrank, but didn't disappear. “No. For hundreds of cycles, maybe thousands, we were the kings. People. We had trucks to move across the land, trucks to swim across the lakes, trucks that moved through the air. We lived in caves we built ourselves, and we decided when it would be light in our caves, and when it would be dark. We controlled the animals. Some of them we raised to eat, like we do with rats now, but some of them we made friends with, and taught to live with us. The ones that were too dangerous, we had weapons to protect ourselves from. Not just knives and hammers, but metal sticks you just had to point at something to kill it. Nobody told us how much food or water we could have, or where or when to work. Everyone could choose their jobs. If you didn't want to be a digger, you could be a driver, or a doctor, or a cook. And people could talk about whatever they wanted, ask any question, think any thought. Can you imagine that?”

         Culver wanted to nod, but couldn't bring himself to lie to Peter. He shook his head.

         “All that was true for one reason,” Peter said. “Because there weren't any hills. We were up on the surface, and they were here, in the earth. We didn't know they existed. But they knew about us.

         “Who knows how long they were waiting. Some people say we fought them, used the metal sticks and charges and everything we had. Some say they just took over, brought us here, just like that. I like to think we fought. I know it's hard to imagine. And don't ever try. That's one of the thoughts they won't let you think twice, if they catch you with it in your head.”

         As Peter fell silent, Culver became aware of noise in the cut, the unmistakable scrape of a boy making his way through. The others were rousing themselves, and beginning to mill around the mouth of the cut. Even Peter heard the boy approaching, unless he just noticed the others, and inferred from them that the boy must be about to emerge.

         Peter leaned close to Culver. His voice was low as he said, “Don't ever let a watcher catch you talking about this stuff. But if you want to know about the surface, what it's like now, ask a hill. I wasn't kidding about that.” Culver though the man would continue, but after a few seconds, Peter straightened, and moved slowly toward the others. Culver followed.

#

         People said there was never a hill around when you wanted one, and for the next few days, Culver found it to be true. Though you could find yourself observed by one of the roving guards or overseers for seven straight days, you could go the same length of time without ever seeing one. The watchers were enough to keep workers in line on a day-to-day basis, reporting as they did to the hills.

         It was four days before Culver came into contact with one. Another day or two and he doubted he would've been able to maintain his resolve. Even now, his first impulse on seeing the hill was to forget the whole thing, and go about his business like the proverbial good human. But he thought Peter would see it in his face, and he couldn't bear to think of the man knowing he'd lost his nerve.

         He was returning to the passage where the team had been working for the past few weeks, where the cut he'd helped make was now almost another tunnel in its own right. A double-bag hung from his shoulders, weighing him down with the team's daily rations of water and sweet-moss and a few sticks of salted rat. He saw the hill from some ways off. It didn't appear to be doing anything in particular, just standing to one side of the tunnel, near a strip of glow. He could tell by the laxness of its body that it wasn't talking to another of its kind at the moment. After his initial hesitation, he took a deep breath, and walked toward it.

         When he was a few feet from it, he stopped, and stared up at its blue-green bulk. He was close enough to smell it. The hills had a mild odor, not even noticeable unless you were right beside them, flat and almost sterile even then, with a slight undercurrent of something sickly sweet, like meat that hasn't quite turned but is close to it. Supposedly they found human odors much more trying, though Culver wasn't sure how they sensed smells, not having anything remotely resembling noses. Something like the way they”saw,” he supposed: with light-sensitive organs spread out across their bodies, hidden beneath their thin outer layer of skin. If they didn't like the way humans smelled, Culver was glad; any little annoyance they experienced was fine with him.

         He pushed that thought from his mind, concentrated instead on his question. He repeated it to himself in carefully chosen language, though he knew from experience that words weren't necessary. What is the surface like? What is the surface like?

         For at least a minute, the hill seemed to take no notice of him, though it might've been staring straight at him for all he could tell. His question bounced around in his head unheeded. Then all at once the hill was there, or Culver was somewhere else; the feeling was impossible to describe. And it was entirely different from being moved around, which you could easily convince yourself had never happened. This was direct and undeniable, a sudden intimacy with an inscrutable mind. Though it always brought on physical symptoms—strong nausea, shortness of breath, tingling and then numbness of the toes and fingers—the worst part was mental: being suddenly confronted, forced to experience, a conception of the world, of existence itself, which was utterly unrecognizable, and which you nevertheless knew was an alien version of the same world you inhabited, and thought you were capable of viewing objectively. That was what stayed with you for days; on some level, forever. Everything you'd ever seen, or felt, or thought, was not wrong, but worse: was one interpretation only, among an infinite set of equally sensible, equally senseless ones.

         He could feel his question being received. The answer wasn't long in coming, though time was difficult to judge under these circumstances. His mind was filled with the hill's thoughts, not quite images, but impressions, the baseless and undeniable impressions of dreams.

         The surface did exist. It was a scoured and lifeless wasteland. It had belonged, once, unimaginably long ago, to human beings. Perhaps other things had lived there, perhaps not. The hills had rendered it barren and incapable of supporting life. Something with the air; there was no air there now, there was only enough air to fill the tunnels and the chambers of the earth.

         This hill had never seen the surface. Somehow Culver knew he wasn't supposed to know that. He pushed deeper, without knowing how, or into what, and found a layer of uncertainty just beneath the intended message. Deeper still, and it was clear that the hill had been instructed to answer as it had, with this rote assemblage of ideas. Its own ideas of the surface were hazy, though Culver could tell the issue was of no importance to it. The hill had been informed that the surface was a place with no ceiling, but it was no more able to conceptualize the idea than Culver was. He pushed as deeply as he could into this corner of what he realized, dimly, dreamily, was the hill's mind, and found an enormous chamber whose ceiling was higher by far than anything Culver had ever been able to imagine, but was still present.

         Belatedly, he understood what he was doing. The shock of fear was real, though still dreamy, as if he were receiving the emotional component of the experience only after a considerable lag. It was like wading in a bathing pool, the simplest movements suddenly slow and cumbersome. He lurched back, withdrawing from the hill's mind as if scalded, and was surprised to find himself still standing in place, his mental movement having had no physical analog.

         He'd never heard of anyone doing what he'd just done, probing a hill's mind as they so easily did with humans, accessing thoughts without consent. It was stunning, but the main point was that it would kill him if the hill had realized what was going on. There was no precedent he knew of, but he had no doubt this would be considered a major transgression, worse and more dangerous than refusal to work or breed, or even violence, any of which was cause for execution.

         He'd never seen an execution, but had heard of many. They did it however the circumstances and their own inclinations dictated, walking a man off a long drop if one happened to be nearby, making him kill himself, or making someone else kill him, with whatever sharp or blunt tool might be in the area. In a matter of seconds, Culver might find himself swallowing dirt and rocks until his throat was too full to breathe, or pounding his head against the unyielding stone of the nearest wall, convinced all the while that he was doing so of his own free will.

         He stared up at the hill, which towered over him, unmoving. It was impossible to tell if it were even aware of his continued presence. He felt his mind slink toward the hill's, anxious to know its thoughts. Horrified, he pulled back before he could tempt fate by entering its mind again. He found himself turning away, and thought, for one hellish second, that the hill was indeed moving him toward some agonizing death. But he was under his own power. He was moving away up the tunnel, even remembering to go in the direction he'd originally been walking. He was aware again of the chafing weight of the double bag on his shoulders, and he grabbed both ends, and yanked down hard, hoping to bury as much of the experience as possible beneath a layer of discomfort.

         When he'd taken a few dozen steps, he glanced back at the hill, which was still standing in the tunnel, apparently doing nothing. That was when he wondered, for the first time, if it would be possible to move one of them around. Before the thought could gain a grip on his mind, he yanked the double bag down harder, and moved off down the tunnel.