Aya came to a halt. "Maybe we should call the others."

"You want Kai to think you're scared of the dark?" Miki snorted, and headed down the stairs.

Aya sighed, then followed.

As they descended, the echoes of their footsteps began to lengthen, a larger space opening up around them. Aya's flashlight played across high arches, like the stone roof of the giant reservoir below the city. For a moment she wondered if the entire mountain had been hollowed out to capture runoff during the rainy season - but why would people building a storm drain look so weird?

Then her flashlight found the cylinders. The room was full of them, in neat ranks like hulking metal soldiers on parade, stretching into the darkness.

"Okay, we found them," Miki whispered. "But what are they?"

Aya shook her head. She walked up to the closest cylinder and pressed her palm against it: cold metal, its surface seamless. When she stood on tiptoe to look at its top, she found no sign of any seal.

"Looks like solid steel to me."

Miki walked past her, a host of shadows wheeling in unison to avoid the beam of her flashlight.

Aya followed her deeper into the army of cylinders, looking for any clue as to what they might be. But the metal forms were unmarked and featureless, like giant pawns in an endless chess set, all exactly the same.

But wasn't there a metal shortage going on? This was enough steel to double the size of the city.

Miki came to a sudden halt. "There it is again."

"What?"

Miki turned and pointed her flashlight past Aya. "I saw a reflection in the metal. Someone's back there!"

Aya spun around, sweeping her flashlight across the ranks of cylinders. Shadows leaped and darted from its beam, but she saw nothing except the reflection of her own half-lit face, warped across the cylinders' smooth sides.

"Are you trying to scare me?" Aya hissed.

"No, I mean it," Miki whispered, her eyes wide in the red glow of their flashlights. "I'm going to get some help."

"Are you sure? Maybe we should...," Aya started, but Miki was already dashing toward the stairs, calling for the others.

Aya squinted into the darkness. Something flickered in the corner of her eye, but when she spun to face it, she saw nothing but shadows scattering from her wavering flashlight.

She took a few quick steps to the side, peering down the next row of metal cylinders. Still nothing.

Cries echoed down the stairs - the other girls answering Miki's shouts. They were coming, but not fast enough for Aya.

She began to walk back toward the stairs, checking nervously over her shoulder. Her flashlight swept from side to side, but that only made the long shadows dance and swivel around her, filling the room with furtive movements.

Then she saw it reflected in a row of smooth metal sides: a black silhouette smeared across them, darting through the shadows.

Aya froze, trying to work out which way the shape was moving, but it was like playing tag in a hall of mirrors.

"Miki!" she called. "I think it's ..."

Her voice faded. The hovering shape had floated into view directly before her, the red flashlight reflecting a familiar pattern of tiny lenses.

It was Moggle.

ESCAPE

"Miki!" she shouted. "It's okay! I don't think there's anything - "

"Don't worry, Aya-chan," Miki's voice called from halfway up the stairs. "They're almost here!"

"Crap," Aya muttered. She knelt, beckoning to the little hovercam. "Come here!"

It wavered for a moment - this new command contradicted its old orders to stay hidden. But when Aya called again, it scooted down the row of cylinders and shot into her arms.

"Hey, Moggle!" she whispered, stroking its sprayed-black plastic shell. "Good job finding me.

But you need to be more careful."

"Are you okay?" Miki's shout came from above.

"I'm totally fine! But I don't think anything's down here!" Aya called back, then hissed, "We have to find a place to hide you."

She switched off her flashlight and shoved it into a pocket, looking around for another exit. But the rows of featureless cylinders stretched endlessly into the darkness.

More shouts came from the top of the stairs. Miki was headed back down, a gaggle of flashlights bobbing behind her.

Aya ducked lower and headed away. The only light came from the Sly Girls descending the stairs, their red and yellow flashlights reflected in the smooth metal curves of the cylinders. Aya covered Moggle with the loose folds of her open jacket.

"When I let you go, find a place to hide. Understand?"

In answer, Moggle flashed its night-lights right into her face.

"Stop doing that!" Aya hissed, stumbling blindly to a halt.

"What was that?" Miki called. "Aya, where are you?"

Aya blinked away spots, standing up to peer across the cylinder tops. The Sly Girls were fanning out randomly across the room.

But Eden Maru was rising into the air, her hoverball rig using the metal cylinders for lift. She flew swiftly across the ranks of cylinders, arms outstretched like the wings of a bird of prey. She would have serious infrared, of course -  most intercity hoverball games were at night.

Aya swore, ducking lower and running as quickly as she dared. She had to get into another room..

But was there any way out of here?

Suddenly Moggle was tugging at her grip.

"Not yet!" she whispered, but the hovercam yanked itself free, pulling Aya off balance. It shot away through the ranks of cylinders like a cannonball.

Aya stumbled to a halt, squinting into the darkness, trying to see where the hovercam had disappeared.

"Lose your flashlight, Nosey?"

She looked up to find Eden Maru hovering just above her.

Aya tried to think of some excuse for putting her flashlight away, but failed. "Yeah, I sort of dropped it."

"Nice going." Eden's eyes scanned the darkness. "So what are we chasing, anyway?"

"Beats me." Aya shrugged, careful not to look in the direction Moggle had fled. "I think maybe Miki's seeing things."

"That doesn't sound like Miki," Eden murmured, her surged eyes scanning the cylinders. Her gaze came to rest in the direction Moggle had flown. "What's over there?"

Aya squinted into the darkness. The other Sly Girls' flashlights were growing closer now, and her unsurged eyes could just make out where the ranks of metal cylinders ended. She took a few steps closer, and saw a meter-wide circle of blackness - the mouth of a passageway.

Aya let out a silent sigh. Moggle must have decided to hide in there. Eden Maru was already on her way, gliding through the air.

"Maybe we should wait for the others," Aya called, jogging after her. "Whatever it is could be dangerous."

"I thought you said Miki was seeing things," Eden said. She landed in front of the circular hole and crawled inside.

As she ran to catch up, Aya realized that the opening was exactly the right size for one of the cylinders to pass through endwise. At its mouth, she felt the familiar pattern of inlaid studs beneath her palms, metal to carry the cylinders on hover-lifters.

Aya crawled after Eden as fast as she could. "Find anything?"

"Yeah. But it doesn't make sense."

A few of the Sly Girls had reached the tunnel entrance behind Aya. Flashlight beams flickered down the tunnel, revealing what Eden had discovered.

A thick metal door stood open, one small window glinting in its center.

Aya frowned. "That's the only door I've seen down here."

"You mean airlock," Eden said, pointing ahead. "There's another one up there."

"An airlock?" Aya shook her head. "Why would anyone have an airlock inside a mountain?"

But as they crawled farther, she saw more metal glinting ahead - another heavy door, standing open just like the first. She swallowed. If this really was an airlock, this tunnel had to be a dead end.

Which meant that Moggle was trapped.

"I better go first!" she said, pushing past Eden.

"But you can't even see!"

Aya ignored her, scrambling down the tunnel. At least she could warn Moggle that someone - judging from the echoing voices behind her, everyone - w as coming.

"Moggle!" she said with the barest hiss of sound.

She slowed a little, trying to listen. Somehow the air felt different in here.

A step later Aya's foot twisted beneath her, coming down wrong on an uneven stretch of floor.

She grunted, reaching her hands out ahead to steady herself...

They touched nothingness.

And then Aya was rolling forward, falling into a void.

SHAFT

Aya dropped in absolute darkness, spinning head over heels into the mountains depths.

She reached for her crash bracelets, hoping they would find enough metal to keep her from splattering. At the first twist, the bracelets found purchase, jerking her upright with a shoulder-wrenching snap. Her feet swung out with unspent momentum, and one cracked against solid stone.

Aya hung there stunned for a moment, pain sparkling against the solid blackness. As her head cleared, the echo of her own breathing pressed close around her. She swung her feet out - they connected with stone, pushing Aya backward into a wall of rock. The impact prized a cry of pain from her lungs.

"Quit kicking!" came Eden's voice from the darkness just above. Seconds later strong arms wrapped around her waist, lifting her up. The agony in her shoulders lessened a little.

"You okay, Nosey?" Eden said.

"I'll live. But maybe no more falling tonight."

"I hope you don't keep trying to get killed just to impress me."

Aya only grunted. As Eden carried her back up through the formless darkness, she felt the tingle of blood rushing back into her hands.

Eden set her down firmly on a ledge - the one she'd just plummeted off. "Maybe you should leave the exploring to people who can see in the dark. And can fly."

"Sure," Aya said, gingerly rubbing her shoulders. "And thanks."

"Thanks again, you mean."

Voices echoed around them - the other Sly Girls were headed down the tunnel.

"Slow down!" Eden shouted. "It's a trap ... or something."

"Yeah, something," Aya muttered, pulling out her flashlight and leaning carefully over the shaft. It was circular, big enough across for the cylinders to travel down. The walls were striped with copper coils as thick as Aya's arm, laid into the stone under clear plastic.

The shaft also continued upward, past where her flashlight faded in the distance.

Moggle had certainly found an odd place to hide.

Eden grunted. "I see you found your flashlight, Nosey."

"Oh, yeah." Aya shrugged. "I guess it was in my pocket all the time."

Eden nodded slowly.

"You found something?" Kai's voice called. She pushed her way past the other Sly Girls crowding the tunnel, crawled to the edge of the shaft, and peered into its depths. "Wow. What is this?"

"I guess we're not sure," Eden said. "Are we, Nosey?"

"No clue," Aya said, rubbing her wrists. "But take it from me - don't jump down it."

Kai crouched there, her hands tracing the metal studs in the tunnel floor. She glanced back toward where the cylinders stood waiting in their rows.

"This must be where those big metal things wind up."

"I guess so," Aya said. "Maybe it's some kind of elevator."

"An elevator with an airlock?" Kai shook her head. "Not likely. Can you see the bottom?"

"No, but I can go there." Eden stepped off into the void, her hoverball rig's lifters catching before she fell even a centimeter. "Sorry to steal all the glory, Kai." Eden smiled as she dropped out of sight.