‘Makes you wonder what kind of beings built it,’ I said. ‘Whether they had the same hopes and fears as us, or whether they were so far beyond us as to seem like Gods.’
‘I don’t give a shit who built it,’ Hirz said. ‘I just want to know how to get into the fucking thing. Any bright ideas, Childe?’
‘There’s a way,’ he said.
We followed him until we stood in a small, nervous huddle under the centre of the ceiling. It had not been visible before, but directly above us was a circle of utter blackness against the mere gloom of the Spire’s underside.
‘That?’ Hirz said.
‘That’s the only way in,’ Childe said. ‘And the only way you get out alive.’
I said, ‘Roland — how exactly did Argyle and his team get inside?’
‘They must have brought something to stand on. A ladder or something.’
I looked around. ‘There’s no sign of it now, is there?’
‘No, and it doesn’t matter. We don’t need anything like that — not with these suits. Forqueray?’
The Ultra nodded and tossed the float-cam upwards.
It caught flight and vanished into the aperture. Nothing happened for several seconds, other than the occasional stutter of red light from the hole. Then the cam emerged, descending again into Forqueray’s hand.
‘There’s a chamber up there,’ Forqueray said. ‘Flat-floored, surrounding the hole. It’s twenty metres across, with a ceiling just high enough to let us stand upright. It’s empty. There’s what looks like a sealed door leading out of the chamber into the rest of the Spire.’
‘Can we be sure there’s nothing harmful in it?’ I asked.
‘No,’ Childe said. ‘But Argyle said the first room was safe. We’ll just have to take his word on that one.’
‘And there’s room for all of us up there?’
Forqueray nodded. ‘Easily.’
I suppose there should have been more ceremony to the act, but there was no sense of significance, or even foreboding, as we rose into the ceiling. It was like the first casual step onto the tame footslopes of a mountain, unweighted by any sense of the dangers that undoubtedly lay ahead.
Inside it was exactly as Forqueray had described.
The chamber was dark, but the float-cam provided some illumination and our suits’ sensors were able to map out the chamber’s shape and overlay this information on our visual fields.
The floor had a metalled quality to it, dented here and there, and the edge where it met the hole was rounded and worn.
I reached down to touch it, feeling a hard, dull alloy which nonetheless seemed as if it would yield given sufficient pressure. Data scrolled onto my visual readout, informing me that the floor had a temperature only one hundred and fifteen degrees above absolute zero. My palm chemosensor reported that the floor was mainly iron, laced with carbon woven into allotropic forms it could not match against any in its experience. There were microscopic traces of almost every other stable isotope in the periodic table, with the odd exception of silver. All of this was inferred, for when the chemosensor attempted to shave off a microscopic layer of the flooring for more detailed analysis, it gave a series of increasingly heated error messages before falling silent.
I tried the chemosensor against part of my own suit.
It had stopped working.
‘Fix that,’ I instructed my suit, authorising it to divert whatever resources it required to the task.
‘Problem, Richard?’ asked Childe.
‘My suit’s damaged. Minor, but annoying. I don’t think the Spire was too thrilled about my taking a sample of it.’
‘Shit. I probably should have warned you of that. Argyle’s lot had the same problem. It doesn’t like being cut into, either. I suspect you got off with a polite warning.’
‘Generous of it,’ I said.
‘Be careful, all right?’ Childe then told everyone else to disable their chemosensors until told otherwise. Hirz grumbled, but everyone else quietly accepted what had to be done.
In the meantime I continued my own survey of the room, counting myself lucky that my suit had not provoked a stronger reaction. The chamber’s circular wall was fashioned from what looked like the same hard, dull alloy, devoid of detail except for the point where it framed what was obviously a door, raised a metre above the floor. Three blocky steps led up to it.
The door itself was one metre wide and perhaps twice that in height.
‘Hey,’ Hirz said. ‘Feel this.’
She was kneeling down, pressing a palm against the floor.
‘Careful,’ I said. ‘I just did that and—’
‘I’ve turned off my chemo-whatsit, don’t worry.’
‘Then what are you—’
‘Why don’t you reach down and see for yourself?’
Slowly, we all knelt down and touched the floor. When I had felt it before it had been as cold and dead as the floor of a crypt, yet that was no longer the case. Now it was vibrating; as if somewhere not too far from here a mighty engine was shaking itself to pieces: a turbine on the point of breaking loose from its shackles. The vibration rose and fell in throbbing waves. Once every thirty seconds or so it reached a kind of crescendo, like a great slow inhalation.
‘It’s alive,’ Hirz said.
‘It wasn’t like that just now.’
‘I know.’ Hirz turned and looked at me. ‘The fucking thing just woke up, that’s why. It knows we’re here.’
THREE
I moved to the door and studied it properly for the first time.
Its proportions were reassuringly normal, requiring only that we stoop down slightly to step through. But for now the door was sealed by a smooth sheet of metal, which would presumably slide across once we had determined how to open it. The only guidance came from the door’s thick metal frame, which was inscribed with faint geometric markings.
I had not noticed them before.
The markings were on either side of the door, on the uprights of the frame. Beginning from the bottom on the left-hand side, there was a dot — it was too neatly circular to be accidental — a flat-topped equilateral triangle, a pentagon and then a heptagonal figure. On the right-hand side there were three more figures with eleven, thirteen and twenty sides respectively.
‘Well?’ Hirz was looking over my shoulder. ‘Any bright ideas?’
‘Prime numbers,’ I said. ‘At least, that’s the simplest explanation I can think of. The number of vertices of the shapes on the left-hand frame are the first four primes: one, three, five and seven.’
‘And on the other frame?’
Childe answered for me. ‘The eleven-sided figure is the next one in the sequence. Thirteen’s one prime too high, and twenty isn’t a prime at all.’
‘So you’re saying if we choose eleven, we win?’ Hirz reached out her hand, ready to push her hand against the lowest figure on the right, which she could reach without ascending the three steps. ‘I hope the rest of the tests are this simp—’
‘Steady, old girl.’ Childe had caught her wrist. ‘Mustn’t be too hasty. We shouldn’t do anything until we’ve arrived at a consensus. Agreed?’
Hirz pulled back her hand. ‘Agreed…’
It took only a few minutes for everyone to agree that the eleven-sided figure was the obvious choice. Celestine did not immediately accede; she looked long and hard at the right-hand frame before concurring with the
