Still, he was the Sapa Inca.

Cura pushed Mardina’s head down. ‘You don’t look him in the eye,’ she said. ‘Nobody looks him in the eye unless he acknowledges them.’

From her peripheral vision, Mardina saw the Sapa Inca throw something out of his carriage. They were birds, she saw, a dozen small songbirds perhaps, but they were unable to fly in the lack of weight, unable to orient; flapping and tweeting, they spun pitifully.

Then one exploded, burst in a shower of feathers.

‘One,’ said Cura breathless. ‘They dose their feed with explosive pellets. It’s quite random—’

Another rattling explosion, a gasp from the crowd.

‘Two!’

And another. The tiny feathers hailed down close to Mardina’s face this time.

‘Three!’

And then a pause – a pause that lengthened, and Mardina seemed to sense, under the noise of the music, a vast collective sigh, as the remaining birds struggled in the air.

‘That’s it! Just three of twelve! The selection is made – number three it is. Look, Mardina, Clodia, the third compartment along …’

Mardina saw the one Cura meant. Standing on the window, above the vacuum, the third bottle contained a girl, slightly younger-looking than the rest, but just as bewildered. Just for a heartbeat she seemed to be aware that everybody in the hall, including the Sapa Inca, was looking at her. Fear creased her soft face.

Then a hatch opened beneath her. The puff of air in her bottle expelled her in a shower of crystals – frost, Mardina realised, condensing from the vapour in the warm air. Already falling into space, the girl looked up, her mouth open. Just for an instant she seemed not to have been harmed. Then she tried to take a breath. She clutched her throat, struggling in the air like a stranded fish, and blood spewed from her mouth.

All this just a few Roman feet from Mardina. People crowded so they could see her through the windows. They laughed and pointed, and some imitated the girl’s helpless, hopeless struggle, as she receded from the window.

‘You are not of our culture,’ Cura whispered in the ears of Mardina and Clodia. ‘But can you see why this is done? Yupanquisuyu seems strong, solid. Yet just an arm’s length beyond this window lies death – the Gaping Mouth. The Sapa Inca reminds us all of what will become of us if we fail to maintain the integrity of the habitat, even just for an instant. And it is just as the gods hover, angry, cruel, vengeful, an arm’s length in any direction from our world. It is only the Sapa Inca and the order he imposes that excludes them from the human world. Do you see? Do you see?’ She stroked Clodia’s head. ‘And do you begin to see, now, child, why it is that you must die?’

The ejected girl had stopped struggling, to Mardina’s relief. She drifted slowly away from the habitat, and then, as she fell out of the structure’s huge shadow, she flared with sunlight, briefly beautiful.

CHAPTER 55

Quintus Fabius walked to the crest of the ridge with Inguill the quipucamayoc, Michael the medicus, and a handful of his men: Titus Valerius, Scorpus, Orgilius the aquilifer with his standard, and Rutilius Fuscus, the century’s trumpeter.

Once more, in the light of the new day, Quintus inspected his position. They were close to the hub here, having completed, with Inguill’s help, their surreptitious journey from the western coast of the ocean by train and other Inca transports. They were in the foothills that characterised this part of the habitat – but just here they were in a relative lowland, a wide valley cut by a river fed by glacial melt. And beyond, the hub mountains rose up, clinging to the steel face of the hub itself.

‘Certainly this ridge is the highest ground in the area,’ Quintus observed.

‘You’re right about that, sir,’ Titus rumbled. ‘The surveyors confirm what you can see for yourself.’

‘Perhaps there was once flooding here,’ Quintus mused. ‘Even a lake. Some of these land forms have a streamlined gracefulness. Is that possible, Inguill?’

The quipucamayoc shrugged. ‘The history of this landscape is of course a question of engineering, not of nature. I do know the landscape artists allowed the country to evolve through stages of its own, letting it form as naturally as possible. We are always aware of the limits of our knowledge. Give the gods of nature room to do what they do best – that was the guiding principle. So, yes, perhaps it was once a lake, in some early stage of its forced formation.’

‘Engineering.’ Quintus looked to where the mountains rose, one range after another, waves of granite topped by gleaming ice – ranges that curved upwards, very visibly, to left and right, as if he was peering through some distorting glass. ‘Yes, one can never forget that this place is an artefact. Now, down to business. War, quipucamayoc, is all about the details – about place and time. As for the place: so, Titus – will this do for you?’

‘The highest ground for miles around, sir, as you say. Let them come to us.’

‘And as for the timing—’

Inguill said, ‘Ruminavi has reported to me that the capacocha ceremony is to go ahead this afternoon, as previously scheduled. Meanwhile my contact Villac the colcacamayoc is ready with the permissions and passes to get your party out through the hub portals to your space yacht.’

Michael said, ‘I can confirm that we managed to get messages out to the Malleus Jesu. We had men volunteer for the details that wash the Inti windows – the details work all day, every day. As the ColU predicted, the little transmitters and receivers in the ear plugs it uses to speak to us were sufficient to exchange communications with the Malleus through the window glass. Trierarchus Eilidh knows what we’re doing; we made a final check last night and she’s ready for the pickup.’

‘Good,’ said Quintus. ‘So all we need to do is get the travellers up to the portal and ready to go. Oh, and fight a battle against the army of the Sapa Inca. So, medicus, what of the men?’

Michael shrugged. ‘The whole of this continent, the cuntisuyu, is at a higher altitude than the antisuyu where we’ve been living – miles higher. The air is that much thinner. However, we’ve rested here seven days. You’ve kept the men very fit. I’d judge that they are acclimatised – and they are as ready as they’ll ever be to fight.’

Inguill frowned. ‘Should I be impressed?’

‘You should,’ Quintus said. ‘You see, quipucamayoc, though a battle itself may seem an arena of chaos to you, victory comes through planning and positioning, as well as reacting to circumstances during the combat.’

‘Like the chess you have taught me.’

‘That’s the idea. And I’m hoping that your generals, who are used to facing nothing more challenging than rebellions by unarmed, untrained, undisciplined villagers, might prove as poor strategists as you are a chess player. We’ll make our stand here. This may be no more than a skirmish – but it may also be the last battle a Roman army unit will ever wage. Aquilifer, set your eagle standard.’

‘Yes, sir,’ Orgilius said proudly.

Inguill anxiously scanned the sky, looking for Condors. ‘The imperial authorities will see that display.’

‘Let them see us now. The die is cast, as Julius Caesar once said.’

Titus Valerius stepped forward. ‘There’s one detail, sir. If we’re to give battle you need an optio. Somebody who’ll be there to kick the arses of the men in the rear ranks, and hold the formation for you. Now, Gnaeus Junius is of course off on the Malleus Jesu. So if I may, I’d like to volunteer for the job. Just for the day, you understand, I’m not angling for a field promotion or a rise in pay—’

Quintus clapped him on the shoulder. ‘You’re a good man, Titus. But if you were to be taking part in this fight today, I’d turn you down; I’d want you at my side in the front rank, one wing missing or not. You’re certainly not getting a pay rise.’