Amber hauled herself up hand over hand up the seemingly bottomless elevator shaft, utilising the serrated servo-assisted gauntlets to grip the stonework. Ahead of her Brannigan was making good progress. She tried not to think about the staggering drop behind her. The bulky pack of extra Blink equipment didn't help either, adding an additional thirty pounds of ballast to her own body weight.

Clamping another ledge, Amber gritted her teeth and heaved, simultaneously moving her right leg up in conjunction to find the next rectangular projection. Why the little ledges jutted out from the walls she didn't know. At first she thought they were the alien equivalent of some kind of emergency ladder, but now that she'd gotten up close to them they seemed to have definite mechanisms built into their outer edges. The face of each ledge bore a series of silver discs arranged in a manner that she suspected was for more than aesthetics – perhaps something to do with the operation of the elevator itself.

Conjecture at this point would get her no-where, however, so she just kept climbing. Luckily growing up in the spires and floating suburbs of Iluvari had driven out any fear of heights she might have had. She closed her mind off to nothing more than the next hand hold; the next platform, moving with the ease of an expert. She'd always excelled at physical activity, even before her enlistment with Blink. The specialised training had honed an already impressive skill set that left her nimbly scampering up the walls.

At least, she scampered until she heard another ominous rumble from below and stopped dead, clamping both gauntlets down against the stone. Within the elevator shaft no-one needed to be warned about the impending shock wave and Amber could see the others above her hugging the walls as tightly as they could. Sure enough, a moment later the whole tower shook. She closed her eyes and clung on.

Clamped to the walls as she was, Amber felt the vibrations shake her to the bones and her teeth rattled inside her skull. The tether around her waist flapped and shook, but she stayed stuck to the wall and waited. Eventually the shaking stopped and she looked up. Lights speared down through the shaft from the head of the group.

"Everybody okay?" she heard Darien call, his voice reverberating around the confined space.

"All good," she shouted back. "But I'd like to get out of here before another quake if that's alright with you."

He didn't answer directly. Instead she heard his voice in her ear piece. "Hammerhead Squad to Manitta-Vanna. Come in please."

"Go ahead, Hammerhead," crackled the reply.

"We've experienced two more tremors since last check in," Darien said, and she could hear the frustration in his voice. "It would be nice if you had some more information as to what the hell is causing them."

"Ah, well," answered Churchwood. "We are still unsure as to what is causing the tremors, but we have zeroed in on the epicentre. There's still no seismic activity, but whatever is causing the quakes seems to be slap bang at the base of the city itself."

Amber stopped sharply at that.

"Wait, it's within the city?" Darien's surprise echoed in her own mind.

"From what we can tell, it would seem so. The epicentre of the forces is not deep enough to be within the crust itself. It's still within our deep readings of the city structure."

"What the hell?" Amber murmured to herself, and she let herself glance down into the bottomless depths of the shaft.

"Roger that," Darien said. "Keep us appraised of any more developments. Hammerhead out." Then he closed the channel and his voice returned to its steely tone of command as he barked an order down the chain of climbers. "Alright, let's keep it moving. Idas, pick up the pace."

Amber didn't need a second bidding – had she been at the head of the group she probably could have hauled the rest of them up through sheer force of will. As it was, she had to follow the pace set by her comrades. While Idas was without a doubt the strongest climber in the group, she was the fastest and moving at his lumbering gait set knots in the stomach. She clambered along, getting as close to Brannigan as she could and trying not to think about the dizzying drop beneath them.

Mercifully, no more quakes struck them during their climb, but Amber was beginning to wonder just how high this tower extended. If felt like she'd been climbing for an age until all she could see was darkness above and below. She reminded herself of the colossal scale of the structure they currently inhabited. Getting anywhere was going to take a while. They doggedly continued on, minute after minute, meter after meter until finally she spotted a glimmer of light up ahead. She tried not to let her sigh of relief sound too obvious.

"Top floor," Idas called from the head of the group. "Everybody off."

Amber cast an exasperated glance upwards. She saw the bulky shadow of her squad mate shimmy around the walls of the shaft and disappear into the half light of the aperture above. One by one the others followed, and she climbed as they did, keeping plenty of slack in the tether. Eventually it was her turn to spiral around back to the inside wall, where an inviting open space waited for them, spilling out with pale light. She reached the last ledge and with a graceful leap, exited the elevator shaft.

When her feet found purchase on solid ground again she gratefully undid the tether from her belt and unclipped the bulky climbing gauntlets. She could feel the sweat on her hands and with a grimace she wiped them against the coarse fabric of her trousers. Bundling the climbing gear back into her bag, she straightened up and examined the space they now stood in.

Her mouth opened in surprise.

The chamber was enormous, ringed by a huge band of glass that revealed the vast depths of Marianas's oceans. Around the room she could see half a dozen other dark apertures in the wall the she assumed were other elevator shafts, but it was what inhabited the main space that really caught her eye.

Arranged symmetrically around a raised central dais were eight stations, each one clustered with the same bulky machinery they'd found down in the corridors. The central platform stood several feet higher, connected by ramps like the spokes of a wheel, and on it an enormous display console squatted, surmounted with a cross-shaped screen. Above that was something that put shivers up her spine.

Larger than any of the others, a monstrous three dimensional carving of the spider creature hung over the central dais. Smooth and excruciatingly detailed, it had withstood the march of time sealed within this chamber. Amber wished it hadn't. The cluster of eyes seemed to bore into her and she looked away, forcing her eyes to wander over the other platforms.

"Why do you suppose they're hanging spiders everywhere?" Idas muttered.

"Seems like some kind of symbol for this place," Darien replied, slowly stepping forward away from the elevator shaft. "Maybe it's some kind of religious icon, you know, like a crucifix."

"According to Churchwood this is the control centre." Hekket looked up from his mapper. "I'd say he was right."

Darien nodded. "Pairs. Niamh, you're with me. Hekket, Idas, circle left. Amber, you and Brannigan go right. Check all the consoles; see if anything in this place is still working."

Amber took the lead, tapping Brannigan on the shoulder as she walked past. The girl fell into line and they circled away through the right-hand platforms. She noticed immediately that these consoles were in much better condition than any they'd seen previously. No dust had settled on this room; the screens were totally intact and a square of lighting nodes illuminated the panels. Power was flowing from somewhere, and it stood to reason that the control centre for the city would be the strongest, built to withstand far more than a series of earthquakes.

Letting her carbine hang by its strap, she leaned close and examined the mechanisms built into the closest console. The panel was a semi-circular shape, with three arcs of oblong buttons of varying size spanning from side to side, each one engraved with a different geometric symbol. On the far left she saw the unmistakable three fingered hand print of whoever had built the city. Amber held out one hand, letting it hover over the depression. The span of the alien hand was almost double hers.

"Do you think that's what activates it?" Brannigan ventured quietly.

"Couldn't say," she replied. "And if it is, I'm not sure we'll be able to turn it on. Our hands don't exactly fit."

"Why don't you give it a try?"

She looked at her impetuous young squad-mate and was about to disagree, when something in the back of her mind stopped her. They were here to explore, weren't they? It wasn't as though she could blow up the city by activating one small console. It had survived uncounted thousands of years; it would survive the curiosities of a group of human teenagers. Chances were that nothing would even happen – if the mechanism responded to DNA rather than just pressure they would be wasting their time.

So she tried to get her hand into the right shape, pressing her ring and pinkie fingers together and spreading the others out. Then she placed her hand in the centre of the depression. The smooth stone felt cold, almost refreshing against her skin. Taking a deep breath, she pressed down.

Her heart jolted when the panel moved without any resistance, sliding an inch further down into the body of the console before locking into place. Then, to her surprise, the surface under her hand lit up with a soft blue glow. Amber jerked back as though she'd been shocked, and waited to see the results of her experiment. The edges of every button along the console began to emanate the same light, but the screen remained blank.

"Seems to have power, but it's still dormant."

"Maybe they need to be initialised from the main console," Brannigan suggested.

She nodded. "Maybe. Check the others."

They tried the other machines on their platform, and sure enough the blue lights came slowly to life under their touch, but the screens remained blank – asleep. With Brannigan in tow, Amber strode up the gentle ramp leading to the central dais, where Darien and Niamh were circling the enormous cross-shaped screen. Doing her best to ignore the statue that loomed overhead, she moved over beside Darien.

"The power is online," she said. "I think if we initialise the main console we can access the others. This must control the whole system."

"I know," he murmured. "I'd just like to be sure what we're turning on."

"We won't know until we try." Amber pointed to the hand print. "That ought to activate it."

"I figured."

She frowned. "Aren't you curious?"

"Yes, yes I am." Darien looked at her and a thin smile crossed his lips. "Nothing risked, nothing gained, eh?"

He drummed the fingers of his left hand against the stone of the console for a moment, then reached over quickly, as though he didn't trust himself to finish the action if he waited too long. He positioned his hand on the print, and pressed down.

The effect was immediate. The enormous screen flared into life and a grid of electric blue appeared over each panel. All around them the satellite stations, too, came alive, their controls shining and their screen displays flickering to show unintelligible bursts of language and images. And above them the eyes of the spider mural shone with power.

There was a moment of silence as the operatives took in what had just happened, until Darien clapped his hands together, grinning like a child who'd just been given a new toy.

He looked at Amber, eyes shining with excitement. "This might just have been worth the trip."