The train slid smoothly out of the station and into watery sunlight.

They soon passed beyond the city limits, heading south, and Penny looked down from above at scattered suburbs of roundhouses, set in a wider landscape of farmed fields, horizon-wide expanses of wheat and other crops tended by huge machines that weeded and watered. The individual farming machines didn’t run on kernels; there was an extensive grid of cables to carry power from central stations. There were people around, of course, this culture didn’t have machinery smart enough to direct itself, but only a few worked in the fields.

Marie said, ‘The Academician was saying that she hasn’t travelled much since she came here.’

Kerys smiled. ‘Your first time on a train, Penny?’

‘Not quite. But I suppose I’ve never thought very much about the nature of your transport systems. Your history, you know, diverged from ours so long ago that much is unfamiliar from the foundations up. Pritanike never had the Romans here …’ Even the Brikanti towns didn’t map onto the ones she was familiar with. For example, Stonehenge here was the centre of a major urban sprawl and transport junction, a very modern city that seemed to have continuous cultural roots going back almost to the last Ice Age. ‘Also you don’t have automobiles,’ she used the English word, ‘by which I mean small vehicles under the control of individuals.’

Ari said, ‘Of course we have automobiles, but they are under the control of the military and the police exclusively.’

Beth smiled. ‘No. That’s not what she means. You don’t have cars. You have tanks.’

Kerys said, ‘It seems there was less conflict in your world compared to ours. We live in a state of perpetual war, declared or undeclared. Our lives are more … militarised. Our cities are fortresses; our transport systems are troop carriers that cannot easily be subverted by hostile forces—’

Mardina snapped suddenly. ‘I wish you’d all stop going on like this.’

Beth looked surprised. Ari glared at his daughter, but kept his counsel, wisely, Penny thought.

In the end it was Kerys who spoke first. ‘Is there a problem, cadet?’

Mardina calmed down quickly. ‘I apologise, nauarchus. It’s just all this talk, it’s so …’ She was visibly searching for the words. ‘Old. Weird. Cobwebby stuff, like you’re all remembering a bad dream.’

Penny covered the girl’s hand with her own. ‘But you can’t blame us for that, dear. I was already impossibly old by your standards when we first came here. Even after all this time on Terra, it’s impossible to put Earth aside. But you’re right; that’s no excuse to inflict our maunderings on you. And I for one need to conserve my energies for the trials to come. Do you have my pillow, Youwei?’

Kerys grinned, and produced a leather pouch. ‘You’re taking a nap? Good plan, Academician. And as for the rest of us, we can while away the time the way soldiers always have – playing pointless games. So what’s it to be? I have knucklebones, chess, cards …’

Penny woke some hours later.

When she glanced out of the window she was startled to find the train was suspended over water. Reflexively she grabbed Jiang’s hand. ‘Oh, my,’ she said in English.

‘Not to worry,’ Kerys said with a smile. ‘We’ve already crossed several bridges – Pritanike is an archipelago, remember. Now we’re crossing the Mare Britannicum. We let the Romans name this stretch of water, since they always built the bridges. You missed Dubru, but we didn’t stop. We’ll shortly arrive in Gesoriacum, on the Roman side.’

‘Impressive …’

The bridge terminus on the Gaul side was a massive structure of ancient concrete, evidently heavily repaired and built over. Penny peered up at scarred walls.

Kerys said, ‘We’ve been building bridges across the Britannicum for a thousand years. Also tunnels under the sea bed. Every time there’s a war the bridges are first to be cut.’

‘Ah. But these foundations remain, to be built on.’

‘And they have got bigger and uglier with every century.’

The train crossed the coast without pausing for custom or security checks, and Penny peered out. ‘So here I am, almost in my nineties, and arriving in the Roman Empire for the first time. What an impossible dream that would once have seemed!’ Staring out at the countryside of northern Gaul, she lost herself in her thoughts.

The others, apparently with relief that the old lady was shutting up, returned to the complicated card game they had been playing.

Gaul, then: province of Rome, as it had been since Caesar’s conquest over two millennia before. The hi-tech monorail cut across a landscape of farms, small fields centred on sprawling villas, and cities, walled towns really, with what looked like ancient and battered fortifications. She tried to identify differences with Brikanti. There was more evidence of monumental engineering; she glimpsed towering aqueducts, bridges, roads laid laser-straight across the green landscape. But this was a blocky architecture of stone and straight lines and rectangles, compared to the more organic Celtic style of Brikanti with its use of wood and thatch. Penny felt a spurt of regret that she hadn’t travelled more when she was younger. Maybe Mardina was right; she had always been too obsessed about the jonbar hinge and the differences from her own lost world to open her eyes and see what was all around her – to let herself relax and just be, to live here in Terra, in this world with its own wonders. But she had brought trouble to this place in the shape of Earthshine, she reminded herself, and that was a challenge she couldn’t duck.

And this world was hardly a utopia, as she could see by glancing out of the window now. Compared to Pritanike, few machines were to be seen in these small fields. But she saw many people working, bent over the crops, carrying baskets of fertiliser or produce, even scraping at what looked like drainage ditches – people everywhere. And wherever the train passed, the people in the fields below stopped their work and lowered their heads, avoiding any chance of eye contact with the train’s passengers.

Ari Guthfrithson, sitting opposite, was watching her.

She raised an eyebrow. ‘You’re not playing the games?’

He shrugged. ‘I fear my fragile relationship with my family would not survive a tense knucklebones contest. Here you are in the glorious realm of Rome. What do you think?’

‘That I’m glad we castaways from the UN-China Culture were picked up by a Brikanti ship rather than a Roman. The people working those fields – starships and slavery. What a contradiction.’

Ari shrugged. ‘When we were able to build machines more powerful than people and animals, we started to grow our economy on that basis, and slavery became old-fashioned. But Christ Himself, according to our Bible, kept slaves. It is not a sin.’ He glanced out of the window. ‘Lutetia Parisiorum is approaching.’

‘I visited this place once,’ Penny murmured, remembering. ‘Before, I mean. When Earthshine brought us here, my sister and myself, to show us the graveyard where our mother was buried …’

‘The rail line parallels the ancient road into the city from the south, which the inhabitants call the cardo maximus. It has always been the Romans’ habit to build their cemeteries outside the city walls.’

After more than twenty centuries of continuous habitation the cemeteries lined the road for many kilometres south of the city.

Even before the train reached the walls, Penny could see that the city was much less extensive than the Paris she’d known. Lutetia Parisiorum was a mere provincial city, not a national capital as in Penny’s home timeline. Still, the urban sprawl was extensive, under a dome of brownish smog.

The monorail cut through the stout walls, close to a road gate huge enough itself to have served as a fortress. Within the city multi-storey red-tiled dwellings crowded along straight-line streets, with spires and domes rising above the rest. Aqueducts snaked over the walls to deliver water, and Penny imagined an equally impressive network of sewers hidden beneath the ground. Many of the grander buildings, with domes and pillared porticoes, either copied the styles of antiquity or, presumably, dated from that long-gone age. But Penny could see more monorail lines laced over the city, and as her train slowed there was a crash of thunder from the sky, a glare of liquid light, as some kernel-powered spacecraft fled over the city towards orbit.