“Explain,” Alexandria said.

“You just, um…” Rose replied. “You cover the board with dominoes?”

Alexandria and Borom shared a look. “Do you get it?” She asked.

“I do not.” Borodin replied.

“It’s like…” Rose said, trying to figure out how to explain it better.

Dexter walked up to the door and pressed the lower left button on the 9x9 grid. Immediately, the button above it clicked down without being touched. Alexandria gasped audibly.

“What are you doing?” she squealed.

“Winning,” Dexter replied, a wide grin spreading over his face. His eyes had a strange gleam in them. “We’re done here.”

“Borodin,” Alexandria said, but her brother was already striding forward. He picked Dexter up like a bag of rocks and carried him away. Dexter didn’t struggle as he was deposited a good six feet from the door. Borodin took a step or two back, planting himself like a guard in front of the puzzle.

“Winning,” Alexandria muttered, calming down once Dexter was away from the door. “Of course. They’re all mad.”

Rose took a deep breath. The situation was getting away from her again. Precision, that was the key. She understood, she could see the answer like a diagram suspended in her mind’s eye, but she needed to lay it out so that everyone else could see it too. If she did it tightly, perfectly, it would be as obvious to them as it was to her.

She reached through her pockets for her least-used treasure, a tiny shard of broken glass. She normally only wanted it when she was talking shop with her Dad. It was still sharp all these years after she’d dug it up. She pressed her thumb lightly against the tip, feeling its clean prick, trying to find the words to say.

“I can explain,” she said in a calm voice, even as her foot continued to scuff the dirt. Everyone turned to look at her again.

“The goal is to press adjacent buttons in turn, until someone can’t press one. Look at the 8x8 grid. Imagine it’s a chess board. Now lay dominoes over the top, until it’s completely covered. We press a button, any button, and Acheron can simply look to see what domino is covering it, and press the other button covered by that domino. So he always has a button to press, right?”

“Uh,” Borodin said, turning to look at the grid. “What if someone has already pressed that button?”

“No, no,” Alexandria said, squinting. “She’s right. Let’s say we press button A. Acheron wants to press button B under the same domino. If we’d already pressed B at some point in the past, Acheron would have pressed A right afterward, so we couldn’t have pressed A to begin with. And Acheron won’t press B until we press A. So B is always unpressed.”

Borodin rubbed the base of his neck. “Huh,” he said.

Rose dug her thumb deeper into the glass. She should have said that, not let them figure it out for themselves. Totalizing precision.

“For the 9x9 board, she continued, keeping her tone steady, “you can cover it entirely with dominoes except for one of the corners. I can show you the tiling in the dirt if you want. So we just press the uncovered corner, then Acheron is playing the same doomed game against us. He presses a button, we look for the covering domino and press its pair. Then he has to lose.”

There was a pause as everyone digested this. “Hm…” Alexandria said, tapping her cheek. “Let me double-check that.”

Rose watched Alexandria take a deep breath, puffing out her cheeks and exhaling. “Alright,” the girl said. “Everyone convinced?”

She turned to Dexter, who nodded absentmindedly, still eyeing the door. Boromor nodded as well, still eyeing Dexter.

“Clean,” Esper replied airily, “and sterile. No beauty, but no falsity, either.”

“Uh, sure.” Alexandria said. “Robin?”

The boy was sitting on his trunk, arms crossed. “Just get on with it,” he said.

“Great.” Alexandria smacked a fist into the palm of her other hand. “Shall I do the honors?”

“Why you?” Dexter asked.

“She’s careful,” Borodin replied. “I trust her.”

“How wonderful,” Dexter deadpanned.

“I’ll check the moves with you,” Alexandria said. “I would have anyway. We’re a team here.”

Dexter rolled his eyes. “Fine.”

Alexandria approached the door slowly. “Alright. We agreed on a vertical tiling above the first line, so we press…this one. Right?”

Dexter moved a little closer to the door, ignoring Borodin’s glare. He squinted at the grid. “Right,” he said.

Alexandria took a deep breath and pressed the button.

click

Acheron led them all around the board, until Alexandria pressed the last button on the grid. There was a pause that seemed to weigh down the cool night air, and then the door swung back, its enormous mass gliding inward with barely a sound.

Rose edged forward. There had been hinges on the inside, like she’d thought. Behind the door was a long narrow passage in the rock, the walls perfectly smooth, as if it had been carved rather than dug. It was eerie.

Her chest was light as she pushed forward past Borodin. “Careful!” he called after her. She felt the walls with her fingertips. Definitely rock, not even a burr out of place. Her thumb left a tiny red streak behind – she must have nicked herself on the glass.

“You’re bleeding,” said Dexter’s voice behind her. She jumped a little, turning around.

“Just a scrape,” she said.

“That was clever, with the dominoes,” he said, turning to look at the door. Acheron’s head still seemed to be staring at them in the torchlight.

“I, uh…thanks?”

“It’s odd,” he continued, pressing the tip of his thumb against his canines. “No dirt on these walls, no grime, nothing out of place. What do you think will happen to that spot of blood? Will it be there the next time this door opens?”

“Um,” she said. “I don’t know.”

“Did you know,” Esper said, wandering up to join them, “that the word ‘odd’ actually means out of place? It comes from the far northern ‘oddi’, which means “an additional one”. The odd one out, if you will, when everyone pairs off. That’s why we call them odd numbers. Just like our starting square. So it’s a little odd to say that it’s odd nothing is out of place.” She smiled, staring at the area just to their left.

“Mhmm,” Dexter replied, uninterested.

Rose didn’t really know what to add to that either.

Borodin strode up, having retrieved their only torch from Alexandria. “Let’s be off!” he said.

“You aren’t proposing we take a burning torch in there, are you?” Robin asked in a petulant voice. “We’ll suffocate.”

Borodin paused, standing right in front of the door. “Will we?”

“I assume so.”

“You assume.”

“How do they light mines, then?”

“I don’t know. But it seems like a bad idea.”

“You assume, but you don’t know,” Borodin said smugly. “Onward! The night is young.”

“That isn’t an argument, you ignoramus.”

“Hey now,” Alexandria broke in, walking in-between them. “Let’s keep things civilized.”

“It’s alright!” Borodin said, clapping a hand on his sister’s shoulder. “Just a little repartee. It’s all in good fun.”

Alexandria rolled her eyes.

“Let me see that torch,” Dexter said. Borodin handed it off to him, smiling broadly at Robin. Dexter walked a foot or two into the mine, holding it up. “The smoke is blowing out the entrance,” he said. “There’s airflow from somewhere deeper inside. We’ll be fine.”

“And what if the door swings closed,” Robin muttered.

“Then we’ll notice the smoke is no longer blowing out!” Borodin replied. “And we can snuff it out then.”

“We’re all going to die in there.”

“It’s certainly a possibility. You can still take the raft back, if you want.” Borodin walked up to Dexter, who handed the torch back, and then strode down the hallway. Alexandria followed behind him. “Come on, Esper,” she said, taking the other girl by the hand and leading her inward. “Watch your step.” Esper came without complaint.

Dexter turned to Rose, raising an eyebrow. “We don’t really have a choice, I suppose,” he said.

Rose nodded, setting her chin.

The two of them followed Borodin. After a few moments, Rose heard a string of curses from behind her, and then the sound of small wheels rolling on stone.

The tunnel they traveled through was long, and sloped very slightly upward as they went. Borodin took the lead, with Alexandria and Esper following close behind. Robin drew up the rear, apparently not wanting to be too close to anyone.

Rose and Dexter walked together, a ways back from the others but in front of Robin, as Rose tried to figure out what to say.

The light was bad, this far back. The darkness and the quiet was oddly intimate. She was getting a sense of Dexter as they walked together. He had a bad slouch, and smelled a little stale. His breathing sped up as they walked; he was probably out of shape. He didn’t seem eager to start a conversation, but he ambled along beside her, not pulling ahead or falling behind.

The prick on her thumb hadn’t quite closed yet, so she pinched it with her finger, using her other hand to fumble for her chunk of iron. When she found it, she took a breath, raising her eyes to meet the side of Dexter’s head as she exhaled.

“So,” she said. “You’re stormtouched too?”

He didn’t respond.

“I’ve never met another one.”

Still nothing. The silence lingered, but she pressed on.

“How, uh, how did you find out?”

She saw him smile in the dim light, an evil smile with too many teeth. “Some people might call that a rude question.”

“Oh.”

“A lot of us, it was the worst night of our lives.”

“Really?”

“Really.”

“You’ve met others?”

“I was in the pen, before I came here.”

“The pen?”

He stopped for a moment, and she stopped with him. “You really don’t know anything, do you?” he asked in a whisper. “How did you even end up here?”

She shuffled her feet, looking at the ground. Her lump of iron felt like just a lump of iron, no strength to be found. She slowly released it.

“I’m sorry,” she said in a small voice.

Dexter began walking again. She hurried to keep up, and they walked in silence for a few long moments, the only sound Dexter’s labored breath.

“Mine was beautiful,” she said, so quietly she wasn’t sure he’d heard. More long moments passed.

“So was mine,” he said. “Beautiful and terrible. I wanted to fly.” She hoped he would say more, but he just continued walking, ignoring her.

“What do you want?”

“Hm?”

“To tell me about it. You don’t want to talk, that’s fine. I’ll trade you something. What do you want?”

Dexter laughed, long and loud and growing louder. He stopped, leaning against the wall, throwing his head back as he cackled. The sound made goosebumps form on the skin of her arm – it was grating and wild, like the whine of metal on stone. The others ahead of them stopped, milling around, and she saw the light grow larger as they began moving back.

“What do I want,” he said to himself, still laughing. “Fuck me, isn’t that the question.” The laughing stopped, and he leaned over Rose, his face uncomfortably close. She tried to draw back, but he grasped her arm, holding her in place. “I’ll tell you what, Rose,” and his heavy breath stank of something sour as he whispered right in her face. “If we get through this? All the way to the end, safe at the foot of the tower? I’ll tell you anything you want to know.”

“Hey!” Borodin’s voice boomed as he approached. “What’s the holdup?”

Dexter released her arm, and Rose drew back. She reached for her stone. Her heart was racing – when had that started? She rubbed her stone, back and forth, forcing herself to take slow breaths.

“Nothing,” Dexter replied. He rolled his shoulders. “Just a little joke.”

“Ooh,” Esper said, oblivious to the tense atmosphere. “I like jokes. Could you share it?”

“No.”

Borodin shifted his footing, wary. Alexandria coughed into her hand. “Why don’t we all stay together?” she asked. “We should wait for Robin, too. These tunnels might be dangerous.”

Dexter shrugged, raising a finger to his mouth and chewing on the first knuckle as he stared into the darkness ahead of them.

Rose stood apart from Dexter as the group continued on, Borodin falling in-between them like a human bulwark. They walked and walked through the soft dark, a gentle breeze still carrying the torch’s smoke away from them. The passage they were in continued, no forks or irregularities, sloping up and up through the heart of the mountain.

Rose distracted herself by trying to figure how far they’d come. An hour of walking, give or take, so probably four miles? Maybe three with their loads. Robin was starting to flag, pulling his heavy trunk up the slight incline for so long, but the small boy didn’t ask for help.

They were on, what, a three percent grade? If they’d already walked three miles, that meant they were almost five hundred feet up. The thought gave her a fluttery feeling in her stomach. She wasn’t afraid of heights. She’d always loved climbing trees, partly for the view. But five hundred feet was higher than she’d ever been.

How tall was the mountain, anyway? She really should have figured that out before she came in. This couldn’t continue forever.

As she was musing, the light finally caught something in front of them. A strange contraption of gleaming metal loomed a few dozen feet down the hall.

The others slowed, but Rose sped up her pace. The others were saying something in low tones behind her, but it faded to a an unimportant hum.

The hallway around the strange object opened up to a circular shape about ten feet wide. Just beyond she could see it continued into a small room. The object itself consisted of a gleaming metal pole through the middle of the widened hallway, with thin bars branching off from it horizontally, each of them almost long enough to touch the walls of the passage. To the left of the pole, more horizontal bars extended from the wall, interlocking perfectly with the bars of the pole, no more than a half-inch of space between them.

Rose reached out and wrapped her fingers around the bars extending from the wall. The metal was cold and smooth. She tried tugging, and there was give, just barely. But not much. Well-made and well-anchored steel, each piece exactly alike. She was reminded of the door that fit so cleanly in its place.

“Rose!” called a voice from behind her.

She touched the other bars, the ones sticking out of the pole to the left. Same radius, as far as she could tell. Same length. Again and again, that eerie precision. She tugged again, rotating the pole in the opposite direction from before, and this time there was movement. The central pole rotated, the bars swinging toward her. It was slow, the weight of the machine being what it was, but she felt no friction. When she pulled far enough, there was a soft click, but no other change.

“Rose,” the voice said again, closer than before.

She tried pushing instead, and a smile spread across her face as she found the trick. When she had pulled the bars moved easily, if slowly. When she pushed, the pole moved clockwise for a moment – and then stopped with a clack. It might be her imagination, but it seemed like it had stopped in the same position where she’d heard the click before.

There was some sort of mechanism under the pole that let it move counterclockwise but not clockwise. Or maybe the mechanism was over it. Had to be careful about assumptions, even small ones.

She felt a meaty hand clap down on her shoulder. “It’s fine, Dad,” she said, patting his hand.

“Er,” came the awkward reply from behind her. She turned to find Borodin, and a pang of regret flashed through her. Right. She wouldn’t get to see her dad for…well, she wouldn’t see him again ever, officially. But not for a very long time in any case.

Borodin took his hand off her shoulder, rubbing the back of his neck. She shuffled her feet a little, feeling her cheeks begin to turn pink. “Sorry,” she mumbled. “I, uh…”

“No, it’s…”

“Just be careful please!” Alexandria’s voice broke in. Rose looked under Borodin’s armpit to see that the others had joined them.

“Sure,” Rose said. She fumbled through her cloak until she felt the surface of her stone, just as smooth as the steel bars had been. “It’s a ratchet.” she said, trying to move the conversation along as quickly as possible.

Alexandria raised an eyebrow. “A what?”

“A ratchet. The center pole’s on a ratchet.”

“What the hell is a ratchet?”

“It’s like a, uh. Hm. It’s like a gear, you know what a gear is? A wheel with little bits coming out of it? It’s a gear with angled bits plus a pawl, which is another little angled bit that goes like, um…” Rose tried gesturing with her hands to demonstrate, but Alexandria just gave her a blank stare. “Let me get some paper,” she said.

“It’s a gear that only turns one way,” Robin said in an annoyed voice. Alexandria turned to look at him. “Like in a clock.”

“Kind of,” Rose said. “The ratchet in a clock is a little different, it has an escapement instead of a pawl. There’s only ever force in one direction on the clock gear, so you don’t need to prevent movement in the other direction. But yes, same idea!”

Robin pushed up his glasses. “I know,” he said, narrowing his eyes. “But it’s still a ratchet.”

Rose opened her mouth, but Alexandria spoke over her. Again. “Fine, I get it,” she said. “So the bar only rotates clockwise?”

“It only rotates counterclockwise in this case.”

Alexandria rolled her eyes. “Yes, fine. So the bar only rotates counterclockwise?”

Rose fidgeted a little. “The difference is important, here,” she mumbled. “The details are always important for things like this.”

Dexter laughed. “‘Things like this,’ she says. As if she does this every day.”

Rose puffed out her cheeks, peeved. The details were important.

Alexandria took a deep breath, letting it out slowly. “Let’s all relax,” she said. “There’s no rush. You’re right, Rose, the details matter. So what the hell is it?”

“Are you slow?” Dexter asked with a nasty smile. “It’s a trap.”

Borodin eyed the device carefully, taking a step back. “A trap?”

“Mhmm,” Dexter said, pacing forward. “That old coot told us the front door was our last chance to turn back, but this–” he tapped casually on the metal, producing a quiet pinging noise – “is where we get stuck.”

“I don’t understand,” Alexandria said patiently, crossing her arms.

“Oh!” Rose squealed. She clapped her hand together a little as everything clicked into place. “I get it!”