At the edge of the roof, she and Miki peered over. A group of three figures had crowded into the narrow space between train and stone, flashlights lengthening their shadows into distorted shapes. Aya realized that they were floating, wearing hoverball rigs like Eden's.

But they hadn't seen the boards. They weren't looking at the train at all. All of them stared at the tunnel wall...

It was moving.

The stone of the mountain was transforming, undulating softly and changing colors, like oil floating on top of rippling water. A sound like a humming wineglass filled the tunnel. The air suddenly tasted different in Aya's mouth, like in the wet season when a downpour was about to start.

One by one, thin layers of the liquid stone peeled away, until a wide door had opened in the tunnel wall.

The figures' flashlights lanced into its depths, but from atop the train Aya couldn't see inside. She heard echoes from a large space, and saw an orange glow from the doorway playing among the flashlight shadows.

A panel in the train slid open, matching the gap in the tunnel wall. The tram settled slightly on its levitation magnets, descending until the two openings were aligned.

One of the figures moved, and Aya jerked her head back into the shadows. When she peeked out again, all three of them had stepped aside to watch a massive object drift from the opening in the train.

It looked like a cylinder of solid metal, taller than Aya and a meter across. It must have been heavy: The four lifter drones clamped to its base trembled unsteadily, carrying it across the gap with the measured pace of a funeral transport.

Before the object had disappeared into the mountainside, another followed, exactly the same.

Then a third emerged.

"Do you see them?" came Miki's soft whisper.

"Yeah. But what are they?"

"Not human.''

"Not... what?"

Aya glanced at Miki's face and realized that she wasn't watching the metal objects floating past.

She was staring wide-eyed at the people down below.

Aya peered through the darkness, and finally saw that the flashlights weren't distorting the figures'

shapes as she'd thought. The people hovering in the gloom were simply wrong - t heir legs absurdly stretched and gangly, arms bending in too many places, fingers as long as calligraphy brushes. And their faces...the large eyes were set too wide, the skin hairless and pale.

As Miki had said: not human.

Aya let out a shallow gasp, and Miki pulled her back from the edge. They lay there side by side, Aya's eyes squeezed shut, her heart pounding as she imagined one of those spindly hands reaching up onto the top of the train and grasping her.

She forced herself to breathe slowly, clenching her fists until the panic subsided.

Finally she slid to the edge of the train once more and looked down, wishing for the hundredth time tonight that Moggle was hovering at her shoulder. But she had only her own eyes and brain.

The inhuman figures still floated there, watching a procession of lifter drones glide from the tunnel door into the train. They carried chairs and wallscreens, food synthesizers and industrial water recyclers, countless garbage canisters. Even a full aquarium balanced between two lifters, the bubbler still rumbling, fish darting around unhappily inside.

Someone was obviously moving out of the hidden tunnel space...but what were those metal things they'd moved in?

At last, the train slid shut, and the air began to hum again. Dark strands wove across the opening in the tunnel wall, like a time-lapse of a spider building a web. Then rippling layers began to roll across them, until the gap was completely covered.

"Smart matter," whispered Miki beside her.

As Aya nodded, the surface shivered one last time, then turned into a perfect imitation of stone.

The flashlights flickered off, dropping the tunnel back into absolute darkness.

"Come on," Miki whispered, pulling her back toward the centerline of the train. Soon it shuddered into motion, and the wind began to swirl around them again. "We'll be jumping off soon, and we can tell the others."

"But who were those people, Miki?" Aya said.

"I think you mean, what were they?"

"Yeah." Aya lay there exhausted in the rumbling darkness, trying to replay in her mind what she'd seen. She needed time to think; she needed the city interface. And most of all, she needed Moggle.

This story had just gotten much more complicated.

RESCUE

"You know, when I waterproofed Moggle, I didn't think you'd ever need it."

"Sorry," Aya sighed. She'd said "sorry" about a thousand times since meeting up with Ren this morning; even she had to admit it was getting old. "Um, I mean, it won't happen again."

Ren dropped his gaze back to the motionless black water. "You still haven't told me how it happened in the first place."

"They must have snuck up on Moggle. They used a lock-down clamp, I'm pretty sure." Aya stepped to the front edge of her hoverboard, peering down. She wasn't even certain if she had the right spot. Her memories of that night were all shadows and chaos, and now Ren's hoverlamps were illuminating the underground reservoir with a cheery glow. Nothing matched the images in her mind.

"They dropped it here, I think."

"They...the Sly Girls, you mean?"

"Yes, Ren, they're real. You just haven't seen them because they don't like kickers very much."

She pointed at the black surface. "Hence my hovercam under water."

He snorted, thumbs twiddling with the instrument in his hands, his eyescreens spinning. Ren made his own trick-boxes, gadgets that could talk to any machine in the city. "Well, they used a serious clamp.

Moggle isn't showing up at all: no city signal, no private feed, not even battery flicker."

Aya groaned, and the sound glanced across the still surface of the water, echoed off the ancient brick walls in a chorus of defeat. The reservoir was even bigger than she remembered, vast enough to store the whole rainy season. Finding one little hovercam down here would be impossible.

"What are we going to do?"

"Well, us tech-heads have a saying: If you can't use the kickest new technology, just use your eyes." He fiddled with his gadget's controls, and one of the little hoverlamps focused into a blinding spotlight straight down into the water. The hoverlamp flew toward Aya, sliding to a stop beside her, illuminating the depths of the reservoir.

Aya eased her hoverboard down to the water's surface and knelt to peer into its depths.

"Whoa ... we actually drink this stuff?"

"They filter it first, Aya-chan."

The water was murky, speckled with suspended dirt and debris carried down by the storm drains. It smelled like damp earth and rotten leaves.

"Does this light get any stronger?"

"Maybe this will help." He flicked his hand, and the hoverlamp descended until its nose broke the surface.

The spotlight grew in intensity, and a half sphere of luminous water bloomed beneath Aya, as if she was hovering above an upside-down sunset in shades of green and brown.

She could finally see the bottom of the reservoir: a fine layer of silt, twigs, and construction rubbish with a few spots of ancient brickwork showing through.

But no Moggle.

"Hmm, this might be the wrong spot."

"Too bad." Ren lay back and stretched out on his hoverboard, staring at the arched ceiling. He raised his arms out in front of him, gesturing through the start-up sequence of some thumb-twitch game.

"Let me know when you find the right one."

"But Ren-chan - "

"See you later, cam-loser."

She started to protest again, but Ren's eyescreens started blinking a full immersion pattern, his fingers flexing and twitching - he was deep in the game.

Aya let out a sigh, stretching out facedown on her board, her chin resting on the front end. She let herself drift slowly across the water, peering down through the luminous muck.

Ren had been right about one thing: This was definitely boring. Every time the hoverlamp obediently followed her, its nose rippled the surface, and Aya had to wait for the water to settle before she could see again. She spotted a few surprising bits of rubbish - a boomerang, the remains of a crumpled box kite, a broken warbody sword - but still no Moggle. She could see why Ren would rather play games than stare into the bottom of a garbage-filled lake.

At least all her test scores yesterday had been aces, and her littlie-watching duty after lunch would build up the last few merits she needed for some black camo paint for Moggle.

When this story finally kicked, she'd be famous enough to never worry about merit-grubbing again.

As Aya peered into the underground lake's mysterious depths, her thoughts returned to what she and Miki had seen last night. What was so secret that you had to hide it in a mountain? And why had those people looked so strange? Even the most serious surge-monkeys never bent their bodies that far out of shape.

The Sly Girls were headed out again tonight to look for clues. Ren had given Aya a spy-cam the size of a shirt button, but it was only good for grainy close-ups. To capture the Girls in all their eye-kicking glory, Moggle had to be sneaking along behind.

Down in the depths, a small silt-covered bump rose from the reservoir floor.

"Moggle?" she murmured, rubbing her eyes.

It was the perfect shape and size, like a soccer ball cut in half.

"Hey, Ren," she cried. "Ren!"

His immersion blinker sputtered to a halt, the eye-screen glaze slipping from his face.

"Moggle's down there!"

He stretched his arms, swinging his legs over the side of his hoverboard. "Great. Time for stage two, which is much more kick."

"Good. I was kind of getting bored."

He smiled. "Believe me, you won't find this boring."

Stage two turned out to involve a tank of compressed helium the size of a fire extinguisher, with a limp weather balloon hanging from its nozzle.

Aya stared at the contraption. "I don't get it."

Ren tossed her the tank, and Aya grunted under its weight. Her board dipped for a moment before the lifters compensated, smacking flat against the water.

"Feel how heavy that is?" he said.

"Um, yes." Water trickled across the board's riding surface, getting her grippy shoes wet.

"That's to solve your floating problem," he explained.

"I have a floating problem?"

"Yes, Aya-chan: Like most people, you float," he said. "It's all that pesky air in your lungs. That tank's heavy enough to carry you straight to the bottom."

She blinked. "Ren, wait a second ... I like my floating problem. I like the air in my lungs! I'm not going down there!"

He laughed. "How else are you going to get Moggle?"

"I don't know," she said. "I thought maybe you'd make some sort of... little submarine?"

"Like I don't have better things to spend my merits on?" He pointed at the helium tank. "There's a magnet on the bottom. Just balance the tank upright on top of Moggle, and it should stick."

"But how do I get back up? This thing weighs a ton!"

"That's the clever part: Just turn this." He drifted closer and gave a valve on the tank a turn. It hissed for a second before he twisted it back. "The balloon fills up, and that carries you and Moggle back to the surface! Pretty kick, huh?"

"Okay. But I can't breathe helium. Where's my underwater mask?" She looked at the open cargo compartment on his hoverboard.

"Just hold your breath."

"Hold my breath?" Aya cried. "That's your awesome tech-head solution?"

Ren rolled his eyes. "The bottom's only five or six meters down - like the deep end of a high-diving pool."

"Oh, thanks for bringing up high-diving, Ren. My favorite panic-making activity." She frowned.