Earthshine snapped, ‘So what do you conclude?’

She stood, clutching a couple of the tubers, brushing the dirt from her hands. Even the texture of the dirt felt familiar. ‘This is Per Ardua. That is Proxima. If there are potatoes here, people must have brought them – people must have been here. But—’

‘But it’s not the Per Ardua you remember. Not quite. If this is the substellar, where’s the UN base? Where’s the relic of the Ad Astra? Yes, you see, I did my homework. Where are all the people?’

‘And where are the builders?’ she mused. ‘Of course, they might have learned to keep away from people and all their works, given enough time.’ She glanced up at Proxima – if it was Proxima. ‘How much time?’ she wondered.

‘This may be another reality strand,’ Earthshine said. ‘Correction: it probably is another reality strand. That’s what the Hatches do, don’t they? Knit up the timelines. Even if it is Per Ardua, this may not be the version of history in which your family pioneered.’

‘Maybe not,’ she admitted. ‘But there have been people here.’ She held out the tubers in her palm. ‘Somebody brought these.’ She broke one of the tubers, revealing crisp white flesh within a sleeve of dirt-matted skin. ‘Looks edible.’ She nibbled the raw flesh, avoiding the skin; it was crisp, moist, cool, all but flavourless.

‘Well, if you live for a few more hours we’ll know if that’s true or not, won’t we?’

‘At least I’m not going to starve here,’ Beth said. The light changed, subtly. She glanced up and saw clouds, thin streaks of white, drifting over the face of the star. ‘Looks like there’s still weather here after all. I’ll make camp.’

She got to work hauling her pressure suit and pack up from the Hatch with her rope.

In the pack she had a pop-up inflatable shelter, emergency blankets, a small stove, and scrunched-up disposable clothes: a space-age Roman legionary’s survival gear, all she needed to endure a few days in the wilderness. She soon had the shelter erected. She shoved the rest of her gear, the pack, the pressure suit, the helmet, inside the tent, and began to haul the whole lot towards the nearest dense-looking clump of trees, seeking anchorage.

Earthlight grunted. ‘I apologise I can’t help with your chores.’ He rubbed his palms together and glanced at the sky. ‘If this is Per Ardua, and I still reserve judgement, it is a quieter Per Ardua. Look at the ground, the soil. The rust colour, like Australia, like Mars. Per Ardua always had a peculiar way of letting out its tectonic energy …’

The continents did not drift on Per Ardua. Perhaps that was something to do with the way this world was tidally locked to its star, the same hemisphere forever bathed in the light, the other forever dark. But there had been internal heat that needed release, as on Earth, and the result had been volcanic provinces, as the ColU had identified them. Every so often a whole chunk of some continent or sea floor would dissolve into chaotic geological upheavals, releasing heat, ash, lava, even building new mountains to be eroded away by the rain.

But, Beth saw, Earthshine was right; this dirt looked old. And that dusty Martian colour in the sky wasn’t the way she remembered it either. It was a long time since any mountains had got built here.

A small voice asked again, How long? And how could that be?

‘But there’s still weather here,’ Earthshine said. ‘Which is logical. The substellar point, directly beneath the star, will always be the hottest place on the planet, always a centre of low pressure, like a permanent storm system. And the antistellar, the opposite point, will always be the coldest – ouch.’ The first few heavy drops of rain fell, pattering on the broad, dead leaves around them, and slicing through Earthshine’s body. ‘I don’t get wet in the rain, but it hurts.’

‘Your software’s consistency protocols.’

She dragged the tent over the ground, trying to get to the shelter of the trees. She saw that the upright cylindrical carcass of the support unit had sprouted open panels, from which manipulator arms had emerged. Small components were being lifted out of the interior of the carcass, while net-like structures were being used to scrape together heaps of dirt. ‘What is it doing?’

‘Wheels,’ Earthshine said, walking slowly beside her. ‘It’s making wheels.’

‘Planning a journey, are you?’

‘Obviously.’

‘Where to?’

‘Away from here. Away from this wrong place.’ His anger was evident now; he said this with a snarl.

She reminded herself that he wasn’t human. Everything about him was the product of software logic of some kind. Yet she wondered too if he had the artificial equivalent of a subconscious. Given the way he’d behaved in the past, including smashing the Mars of the Rome-Xin history, that would explain a lot. So maybe his anger was genuine, the display unconscious.

At the fringe of the forest clump she found a couple of stout trees ideally positioned to anchor her shelter. She took lengths of her rope and began lashing the shelter to the trunks. The trees at least were as she remembered them, basically expanded forms of the ubiquitous stems. ‘If this isn’t Per Ardua it’s a damn good impersonation,’ she muttered as she worked.

By the time she was done the rain was coming down harder, hissing on the leaf-carpeted ground. She looked back at the Hatch, whose lid, she saw, was closing. ‘The Hatch is a spacetime artefact, and yet its designers took care that it’s protected from the rain. Well, that’s attention to detail for you.’ But there was no reply, and when she glanced around she saw that Earthshine had already retreated to the interior of the tent.

Beside the Hatch, in the rain, the support unit was rapidly assembling big skeletal wheels, four of them.

CHAPTER 40

The reception chamber was meant to impress, Mardina thought. If not to awe. Even before you got into the main body of the Titan, the huge space habitat itself.

The chamber was a wide, deep cylinder set precisely at the spin axis of the rotating habitat, with zero-gravity guide ropes strung from wall to wall. To reach this chamber you had already had to pass through a series of locks, each of which alone had been larger than any single cabin in the Malleus Jesu. The place was ornate, too, with rich woven blankets spread over the steel walls, and sprays of brilliantly coloured feathers, even the gleam of gold and silver plate. The huge face of some angry god, his eyes picked out by emeralds, glared down at the Romans from the opposite wall.

And, from glass-walled emplacements all around them, troops stared down at the newcomers. They wore a uniform of a simple shift tied at the waist, brightly coloured, and functional helmets of what looked like hard steel. They had weapons to hand, short swords and stabbing spears – even some kind of artillery, and blunt muzzles peered at the Romans from all sides.

And now the stranded Malleus personnel – forty legionaries with their Centurion Quintus Fabius, Mardina, Titus Valerius and his daughter, Michael the Greek medicus, and Chu Yuen with the ColU in its pack on his back – were huddled in this vast arena, tangled up in the guide ropes like flies in a spider web. It didn’t help that all of them had been cleansed before being allowed this far into the habitat – stripped naked, bathed in hot showers, their clothes shaken out in the vacuum. The ColU said it was entirely sensible that the controllers of this enclosed world would try to keep out fleas and lice and diseases. But it had taken all of Quintus’s personal authority to persuade his men to submit to this. The Romans, in their military tunics and boots with their cloaks and packs, looked like savages in this setting, like the barbarians they effected to despise. At least they didn’t look like soldiers any more. Well, Mardina hoped not. At Quintus’s orders the legionaries had left behind on the Malleus Jesu their gladios and spears and fire-of-life weapons, and their armour, even their military belts and medals.