‘I don’t think you’re helping, Mardina,’ Quintus growled.

‘And the jonbar hinge Stef Kalinski spoke of, when she discovered she had a sister she had never suspected existed before. That’s six!’

‘Thank you, Mardina.’

The ColU said, ‘Clearly these histories do not coexist, but they overlap, to a small degree. Scraps of one may be discovered in another.’

‘Like my Ares insignia,’ Inguill said.

‘Yes,’ Quintus said. ‘And like my own century, my ship, which survived one jonbar hinge.’

‘And myself and my companions,’ said the ColU, ‘who have survived two hinges … Quipucamayoc, we have taken to calling the transitions between worlds jonbar hinges. The derivation is complicated and irrelevant.’

Inguill tried out the words. ‘Shh-onn-barr hin-ch. Very well. A name is a name. But to label something does not mean we understand it.’

‘Indeed,’ said the ColU. ‘The replacement of one history by another is not a tidy matter. Scraps remain.’

‘Do we know how these transitions are made? How one history is cleared away, like a dilapidated building ready for demolition, to be replaced by another?’

‘Judging by our experiences, the termination of one history is generally accompanied by disaster. War. The release of huge energies from the kernels – which you call the warak’a.’

‘Which is something to be avoided.’

‘Yes—’ Quintus growled. ‘Who is making these transitions happen is a more pertinent question, perhaps.’

‘Very well – who, ColU?’

‘We don’t know. Not yet. We have some clues. Inguill, you said your people on Mars – Illapa – discovered a new field of warak’a, a new Hatch – our word for the portal you found.’

‘Hat-sch. Very well. We know how to build them, of course.’

‘As did we,’ Quintus said. ‘We Romans. You jam the kernels together—’

She waved a hand at the artificial sky. ‘Our ships roam the stars. Everywhere we go we take the warak’a – of course, or rather they take us. And everywhere we go we build Hatches.’

‘As did we,’ Quintus repeated.

‘But why?’ the ColU asked. ‘Why do you do this? Who told you to?’

Inguill glanced at the Roman, and both shrugged. Inguill said, ‘The warak’a are a gift from Inti, the sky god. That seems evident – a rare benison from our gods, as opposed to a punishment. And the Hatches are always found with them. Wherever we travel we make more Hatches as a tribute to the gods. It seems to work … At least, we have not yet been punished for it, so we deduce this is the correct course of action.’

‘As with us,’ Quintus said. ‘Though you seem to be more industrious at it than we ever were.’

‘Yes,’ the ColU said. ‘That’s it. Whatever the nature of the change, whatever the cultural details, each new draft of a civilisation is better at building Hatches. My culture, as far as I know, built no Hatches at all. You Romans did pretty well. And the Inca—’

‘We litter worlds with the things,’ Inguill said. ‘This is the triumph of our culture. And now I discover that we have been somehow manipulated to achieve precisely this goal? Our whole history distorted!’

Mardina studied her. ‘And that makes you feel …’

‘Angry, child. Angry. Whoever is doing this, it is hard to believe it is a god. For what god needs a door in the ground?’

Mardina herself felt oddly exhilarated. The flood of revelations and new ideas made her feel as if she was jumping recklessly off a cliff edge, or diving from the axis of Yupanquisuyu and plummeting to the ground, laughing all the way down …

The ColU said, ‘Inguill, your discovery of a Hatch on Mars, Illapa, has changed everything. Because when we emerged into this time stream, past the latest jonbar hinge, it was just as a Hatch appeared on Mars. That was on the Romans’ version of Mars. This new Illapa Hatch is an obvious link to the underlying … strangeness. Well, we must pursue Earthshine—’

Inguill frowned. ‘Who?’

‘I’ll explain. But for now we must get to Illapa.’

‘How?’ asked Inguill bluntly. ‘The imperial authorities would not allow it. Even I could not authorise it.’

‘I have a plan,’ said Quintus Fabius smugly.

When the centurion had explained his ideas, it took a while for Inguill to stop laughing.

‘Are you insane?’

‘Oh, quite possibly.’

She looked at him, smiling. ‘This was your plan all along, wasn’t it? To lay up here in Yupanquisuyu, steal some food, fight your way out, and fly off into space, to found some new Rome of your own? Ha! No wonder you Romaoi rolled over when the Inca armies landed on your shores. Look – you won’t get as far as the ocean. The awka kamayuq patrols will stop you.’

‘All right,’ Quintus said angrily. ‘Then do you have any better ideas?’

‘Well, I’m prepared to concede you need to get to Illapa, if Collius says so. We humans together need to understand the agent that is meddling with our destinies. But you’re not going to walk out of here.’ She sighed. ‘The Sapa Inca’s advisers would do nothing to help. They are pretty fools, angling and manoeuvring, of no intellect or ability. Conversely the administrators who actually run the empire are just that – quipu-pluckers, with no imagination whatever. Which leaves the task to me – and you. For the only way you’ll do this is if I help you.’

Quintus frowned. ‘You would do that? How can we trust you?’

‘We have no choice, Centurion,’ the ColU said. ‘I see that now.’

‘And I barely trust myself,’ Inguill said, a little wildly, Mardina thought. ‘At the very least I will be committing a crime by smuggling you out of here – out of the light of the Sapa Inca’s rule … And at the worst, I suppose, my meddling might itself result in one of these catastrophic changes you so eloquently described. On the other hand, if I manage to slay this particular jaguar, a greater service to the empire is hard to imagine. Perhaps history will forgive me—’

‘If history survives at all,’ said the ColU.

‘Indeed.’ She stopped pacing and faced Quintus. ‘In some ways it is what we share that interests me, rather than what divides us. We both sail the seas of space; we both build the ColU’s Hatches. We both name planets after our antique gods. And we share other legends – so my spies inform me.’ She glanced up at an Inti window. ‘We call the nearest star to the sun just that – Kaylla, which means “near”.’

‘As we call it Proxima,’ said the ColU. ‘Meaning “nearest” in Quintus’s tongue.’

‘And our sailors of space have a legend of the furthest star of all, where the gods lay their plans against us, or plot the catastrophes of the end of time: the pachacuti. We call this undiscovered star Karu, which means “far”.’

‘As we speak of Ultima,’ Quintus mused. ‘Yes. We do have much in common.’

‘And is Ultima where we will find the Hatch builders? I must get back to Cuzco. There’s much to prepare if we are to pull this off, and the more time they have to fester, the more plots tend to unravel. But we need more … We need a way to divert the attention of the Sapa Inca and his advisers at Hanan Cuzco from your break-out attempt.’ She looked now at Mardina. ‘And, given what Ruminavi has belatedly confessed to me about his mit’a collecting in your ayllu, or his failure there – if I am risking the sacrifice of everything, my career, even my life, I must ask you to risk a sacrifice too.’

Mardina frowned. ‘Me?’

‘Not you, child. Your friend, Clodia Valeria. You must be prepared to sacrifice her. But you, Mardina, may be the key to making it happen …’

CHAPTER 51

Before beginning the march to the ocean, Quintus Fabius inspected his troops.

As the trumpet sounded, the men of the century formed up in orderly ranks, their cloaks on their backs, their marching packs at their feet, their improvised or purloined weapons at their belts. This was the first time they had turned out as a proper unit of the Roman army since arriving in this habitat.