'It could be a drain,' George said.
'With miniature wooden barges?'
'Miniature barges?' Aubrey said. 'What on earth?'
'I assume they're barges. They might be just boxes.
They're definitely manufactured, and just like the rails, they disappear into the middle of that thing.'
Aubrey looked up, then down, then all around. 'From all directions, they go in there.'
'It depends on how you look at it, old man,' George said. 'They could be leaving the middle of that thing and going outwards.'
'Or some might be pumping inward, and some flowing outward,' Caroline said.
Aubrey's head started to ache with the possibilities. 'But pumping what? And flowing what? Water? Electricity? Steam? What's going in? And what's going out?'
'Boats?' George said. 'Maybe it's a strange new communication system that uses miniature naval craft to convey information.'
'That is probably one of the more bizarre suggestions I've heard for a long time,' Aubrey said, 'and I'm frightened because I'm considering it seriously.'
'Naturally,' George said, looking pleased with himself.
'But whatever else it is, it's a mystery.'
'It's only a mystery until we find out,' Caroline said.
'And how are we going to do that?' Aubrey said. 'It's a maze in there. A ferret couldn't squeeze its way through.'
'If we can't go through and it's pointless to go around,' Caroline said, 'then we must go over. A better vantage point, a position of strength. We may be able to see into the centre from up there.'
Aubrey raised his head, then leaned back. It was difficult to tell in the shifting light, but it looked as if the structure ended a good ten feet before the ceiling.
Caroline grinned. 'Let's see how you two are at climbing.'
The going was reasonably simple, at first, and Aubrey certainly found it easier than climbing most trees. Solid, rigid pipes were always close at hand, and if he put his weight on something that flexed ominously, an alternative was always nearby. Many pipes were conveniently sized for gripping, but even the large bore mains were simple enough to clamber over. Chains and cables infested the meshwork, too, and provided useful handholds.
But to Aubrey's increasing unease, he found that many of the interweaving strands carried traces of magic.
He avoided wires, singly or in bundles. He had a healthy respect for electricity, as he did for most things that could kill him. Whenever he saw the bright copper mesh, he kept well away from it.
They climbed straight up the outside of the structure.
Caroline went first, offering advice to both Aubrey and George as they followed. She appeared to have no difficulty with heights, and often hung from one hand as she looked back to check their progress.
George climbed doggedly, muttering under his breath each time he came to an obstacle that had to be skirted or squirmed around.
Aubrey climbed a few yards away. A construction that looked suspiciously like a miniature aqueduct appeared just above him, emerging from the wall opposite and disappearing into the depths of the labyrinth. Aubrey hoisted himself up and found that it was, indeed, open on the top and carried water. He added it to the list of unbelievable things he'd recently seen.
Once on top of the structure, the going was easier. Instead of lifting their own weight, all they had to do was scramble on all fours. They had to work around any pipes, wires or cables that thrust down from the ceiling (or up from the mass below?) and they had to be sure anything underfoot would bear their weight, but the challenges were few.
Aubrey found himself staring downward as he went, admiring the intricacy that resulted from the myriad interconnections. At times he thought he could detect movement, but he decided it could simply be water, or one of the miniature barges Caroline had seen.
Caroline paused and glanced back quizzically. Heart pounding, Aubrey nodded, then crawled until he could see that she had reached a gap in the structure. He sought the walls of the chamber and realised they'd reached the centre of the immense meshwork. He found a good foothold on what felt like a solid concrete beam and gazed at the light that filled the gap.
He had to shade his eyes. The light was fierce, a flickering, dancing radiance that licked upward like a bonfire on Empire Night. Aubrey felt its power even at this distance and it daunted him. It wasn't heat that battered his skin, it was raw magical power, redolent with potential – and a hint that was unmistakeably Dr Tremaine.
Gritting his teeth, he crawled closer until he could see more.
A column of cold flame, white and blue, writhing and spinning, filled the gap in the lattice. Mostly, it was half the height of the array, but it occasionally burst upward, as if in joy, sending an arm of flame lancing toward the heights.
'I can see someone down there,' George said.
Aubrey started and nearly lost his grip. He hadn't heard George approaching.
'How many?'
'Just one, I think.'
Caroline made a sound deep in her throat. 'It's Dr Tremaine.'
She lifted her head and scanned the area. It was obvious to Aubrey that she was looking for a way down.
She wasn't about to shirk a confrontation with the man who killed her father.
Aubrey tried to think of a good enough argument to change her mind, counselling caution over impulse.
He blinked and almost smiled when he realised that this was just the sort of advice he'd ignored over the years, from some of the best.
Caroline glanced back the way they'd come and her face fell. 'Oh.'
Aubrey followed her gaze and immediately saw the danger. He did his best to appear steely calm, turning a groan of dismay into what he hoped was a determined grunt, while his whole being insisted that elsewhere (anywhere!) was a better place to be.
A swarm of glittering motes was speeding toward them. Insects was what immediately came to mind – bees or wasps – and Aubrey became aware of a humming that was quite different from the background noise from the structure. It was an angry sound, full of intent. The swarm bent in their direction and the humming became furious as it dived.
Aubrey started scrambling on all fours, grasping whatever came to hand. Finding action a good antidote to terror, he set off in a different direction to Caroline, trying to draw the swarm away. He hoped George would do the same and perhaps one of them could escape.
He'd only managed a few frenzied yards when one of the insects struck him behind the ear with stunning force. He fell forward, barely catching himself, then he was struck again, just under the shoulder blades, and he grunted with pain.
It felt as if he were being pelted with stones.
A pistol sounded, once, twice, three times in quick succession. He hoped it was Caroline and he hoped she'd done some good.
One of the insects struck the pipe he was clutching and it rang like a bell. He stared and saw that it was, indeed, a winged insect – but it was made of bright, coppery metal. The insect was chillingly unformed. No features, no details apart from the segmented body, legs and wings. It staggered a little, as if dazed, then it dropped off the pipe and vanished into the depths of the structure.