Clodia asked, ‘Help you with what? What is this thing?’

‘A door in the world …’

As the three of them heaved, the plinth toppled back – to reveal a steel-walled tunnel leading down into the ground, set with scuffed rungs. There was a smell of oil, the sharp tang of electricity.

‘The underbelly of the world,’ Ruminavi said admiringly, and he rapped a rung with one knuckle. ‘Which we call the xibalba, the underworld. Two centuries old, and still as sound as when it was built. And there’s a lot of it, miles thick in some places. Down you go. I need to be last in, so I can lock us tight once more.’

Again Clodia and Mardina hesitated. Again they gave in, and followed his lead.

Mardina went first. ‘Just understand this, apu. I trust you only marginally more than I distrust you.’

‘Understood.’

‘And if any harm were to come to Clodia because of all this, her father will pull you apart like a spider in a condor’s beak.’

‘I don’t doubt it – down you go, Clodia, hurry, they are close! – but it is harm to Clodia especially that I am trying to avert. Are you at the bottom? The light dazzles up here … Good. I’m on my way.’

He clambered briskly down the rungs, and pulled the lid closed. As the heavy plinth fell back in place, the lid slammed shut with an ominous clang. To seal it, Mardina saw that he turned a wheel rather than use his key – good, they had a way out of here, whatever Ruminavi did.

At the bottom of the shaft, Mardina found herself standing in a corridor dimly lit by fluorescent tubes, many of which had failed, creating islands of darkness. There were piles of litter here and there, heaps of tools, a few discarded bits of clothing. The walls themselves were scuffed, dented and scarred, scratched with graffiti. It was a dismal prospect.

And the corridor seemed to run to infinity in either direction. Mardina felt Clodia’s hand slip into hers.

Ruminavi heaved a sigh. ‘Well, we’re safe now. Come on, there’s a rest station just down here.’ He led the way, his booted feet clattering on the bare metal floor, his voice echoing. ‘The troops and the assessors think I’ve gone to spy out the forest. I know how long they plan to be at this ayllu; I’ll bring you back out when they are safely gone.’

They had to hurry to keep up with the apu. Mardina said, ‘Seems a good way to this rest station of yours.’

He snorted. ‘You’re not wrong. But you’ve no idea how long this corridor runs.’ He pointed. ‘All the way back to the Hurin Cuzco hub that way; all the way to the ocean that way. This is one of the main subsurface arteries – aside from the big vehicle access ways, that is. There are even some ways that pass under the ocean to the cuntisuyu. Here we are …’

The rest station was basic, a few scuffed benches, cupboards empty of any trace of food save a few crumbs, a spigot that dispensed warm water, a quipu hanging from a nail – maybe it was a work schedule. A single light overhead made everything seem washed out, dead; Ruminavi seemed even more wormlike than usual. But if this was some kind of trap, she and Clodia had walked right into it, Mardina reminded herself.

Mardina and Clodia sat uncomfortably, nervously, side by side. Mardina asked, ‘What is this place, apu?’

‘Can’t you guess? Maintenance – that’s what all this is for. The hull of the Yupanquisuyu is riddled with tunnels and access ports, and the tremendous equipment needed to keep the world working.’

Clodia stared. ‘What kind of equipment?’

‘Machines that do all the things a planet will do for you for free. Consider rainfall on the hub mountains. Every drop that falls dislodges a speck of rock. In time the mountains are worn away, and all their substance washes into the sea. On the world you call Terra, all that eroded silt is compressed and heated and passed in great currents of liquid rock beneath the surface, until it is thrust back up, as lava from a volcano, as a stupendous new mountain of granite. And so on, all entirely natural, the very mountains rebuilt. Here, the rock would just wear away, and the ocean would clog up, huge deltas spreading out from the cuntisuyu and antisuyu rivers until they met in the middle – if we let it happen. And so we have machines to gather the eroded waste, and ducts to pipe it back to the mountaintops, and sculpting machines to spray out new rock layers … That kind of thing.’ He smiled. ‘The architect of this world allowed himself to be called Viracocha, who is our creator god. But he was not Viracocha – or rather, the man alone was not the god, but we all are, all the generations since who have laboured to keep the world working.’

Mardina tried to imagine it. ‘So the whole of the hull of this great ship is embedded with vast machines to maintain the world.’

‘That’s the idea.’

‘And where there are machines to maintain the world, there must be people to maintain the machines.’

‘Hence the hatches – there are access ways near most of the larger tambos. Maintaining the infrastructure machinery is a mit’a obligation, though we do use yanakunas for the more dangerous and unpleasant work. Cleaning out the great ocean-floor silt ducts, for instance – that’s a great eater of humanity. Or the antis. They aren’t much use for anything else in terms of the mit’a, save the capacocha of course.’

Mardina didn’t know what he meant by that: capacocha.

He smiled at them. ‘I’ll tell you a secret. We’re planning to use your own people in the under-machinery, eventually. Well, you were miners of ice moons, or you say you were; you are used to working with complex machinery in tight spaces. And you look strong, able to endure. We haven’t done this yet because we still don’t quite trust you. We don’t want rats in the foundations of the palace, so to speak.’

Clodia said, ‘The antis. Who you say are no use for anything—’

‘I suppose that’s unfair. They harvest certain plants and animals for us that grow wild in their forest. They are fine archers, and that can be useful. And in their way, I’m told, they help maintain the health of their forest. All that burning and cutting they do is itself part of a greater cycle.’

‘They worship Jesu,’ Clodia said. ‘As we do.’

His smile returned. ‘Ah, yes! You noticed that, did you? The slave god on His cross. They picked it up from you Romans, of course: those of your ancestors who once crossed the ocean to come to our country, to the antisuyu jungle. The Romans were successful for a while; they built their coastal cities and explored the river valleys. But then they, or at least your government and its legions, withdrew from our lands, leaving only relics, survivors. When our own expansion into the antisuyu came some centuries later, we learned a great deal about the lands across the sea from the babbling of the degenerate descendants of the colonists, before we took them as yanakunas or otherwise absorbed them. But the antis had encountered those wretches first, in their forest – and with the antis they did leave a more lasting legacy, which is the worship of your slave god. Perhaps it is a consolation for them now, as they endure their miserable lives in the jungle.’

Mardina glanced at Clodia. ‘Or perhaps it motivates them to help others. Help on which you relied the first time you saved us from the mit’a party, apu.’

‘Well, perhaps.’

‘But you still haven’t told us what it is you so bravely saved us from.’

‘Well, more specifically it is Clodia. You are the exact right age, and your pale colour, and your beauty, child, make you a perfect tribute offering.’

Clodia looked confused and scared. ‘An offering for what?’

‘The capacocha is part of the mit’a tribute, to the Sapa Inca. A special tribute – a gift of children. And if your child is chosen, you must give up her or him gladly, and sing songs of thanks and celebration when the end comes.’