Mardina looked around the room, at her mother, at Jiang, even Kerys – at stunned faces. She touched Kerys’s arm and whispered, ‘Nauarchus …’

‘Yes, cadet?’

‘Everybody seems amazed by all this. But it’s just a bunch of old ruins under the ocean, isn’t it? What difference does it make?’

Kerys looked at her curiously, almost fondly. ‘Ah, Mardina. Evidently you entirely lack imagination. You’ll go far in the Navy.’

‘I’ve seen this before,’ Penny said now, still searching her bag. ‘Oh my memory, I should have made the connection days ago. The motif of your Drowned Culture, the circles and bars. Earthshine showed me before. When he took us all down into his bunker under Paris, before the Nail fell.’ She closed her eyes. ‘And he had a plaque on his wall, some kind of rock art, etchings in sea-corroded concrete, the first time he brought the two of us to Paris – oh, years earlier, my sister and myself. And he brought the plaque with him on the Tatania.’ At last she found her slate, tapped it with bony fingers, and showed them an image. It was a brooch, Mardina saw, a bit of stone, marked with concentric circles and a radial groove. ‘Earthshine was wearing this on Mars eight years ago. And in meetings I had with him, Before.’

Ari frowned. ‘Earthshine? Then somehow he knows about the Drowned Culture already.’

‘Yes.’ Penny pursed her lips. ‘But you don’t get it, you don’t see the bigger picture, Ari. Earthshine must have already gathered evidence of this “Drowned Culture” from Earth. From my history. Not from Terra. Do you see? It is as if our divergent histories are not organised in any kind of linear fashion, an orderly sequence, so that one gives way to the next, and then the next. They are like … ice floes on a frozen ocean, bumping up against one another in a random way. But I suppose if Earthshine is right that the kernels are wormholes – if in fact we live in a universe riddled with wormholes – then this kind of chaos is what we must expect.’

Ari looked doubtful. ‘Wormholes? I’m afraid I don’t understand.’

‘Connections across space and time, even between universes … If you have such links then causality can be violated. Cause and effect disconnected, mixed up. Even archaeology need not make sense, as we see here, because its basic logic, that whatever lies beneath the ground was put there by somebody in your own past, need not apply any more. Anything is possible; history is ragged …’

‘Chaos,’ Kerys said. ‘The signature of Loki. In whom officially, as a Navy officer in a Christian federation, I don’t believe at all.’

A junior officer burst into the room, looked for Kerys, and thrust a note into her hand. She looked over it quickly and frowned.

‘But if all this is true,’ Mardina said practically, ‘what are we supposed to do about it?’

Ari said, ‘We could ask Earthshine.’

‘Yes,’ Penny said. ‘Obviously. But what is he intending? And what has Ceres got to do with it?’

‘Maybe we’ll find out more soon,’ Kerys said grimly. ‘Just when I thought this mess couldn’t get any odder …’

Mardina asked, ‘Nauarchus? What’s happened?’

‘A Roman vessel has just returned from interstellar space. Twenty-five-year Hatch-building jaunt. And at their target system they found strangers.’ She looked round at the group.

Beth asked, ‘Strangers?’

‘They were speaking your tongue. English. Knowing about you, the Roman authorities have asked for our help.’

Beth, Jiang, Penny, survivors of the Tatania, shared stunned looks.

Kerys stood up. ‘Well, we need to deal with this. Cadet, you’re with me. I’m afraid your formal induction is going to have to wait for another day.’

She hurried out of the room, and Mardina ran to follow her.

CHAPTER 24

The Roman exploration vessel Malleus Jesu was directed to land near Lutetia Parisiorum, in Roman Gaul. And Penny and her companions were to be brought to the city to meet the ship’s strange passengers.

Penny prepared for the journey, slowly gathering her old-lady stuff, her favourite quilted blankets and duck-down slippers, the pills and ointments and mysterious poultices supplied to her by the local doctors for her various aches and pains. She wondered what strings had been pulled to achieve all this, to bring together the survivors of the Tatania, and now these other individuals found on the planet of a distant star by Roman explorers – a dialogue between two governments already wary of each other and dealing with an existential mystery that had dropped out of the sky into their hands. She supposed the calculation was that at least the encounter might yield information. And, she supposed, that was what she was hoping for too, at the minimum. What was she doing here? How did she get here? What did all this mean? … As for herself, she had long ago given up hope of ever going home again. She knew she would die here.

She hadn’t expected to see her twin sister again, however. Yet Stef’s was among the names reported by the Navy.

And what were they to do about Earthshine?

As she finished her preparations, she had no doubt Earthshine was very well aware of all that was going on, and would be monitoring closely.

They were to travel from Eboraki, in the north of what Penny would have called England, to a city called Dubru on the south coast. And from there they would cross into Gaul.

With Jiang and Marie Golvin, Penny was brought from her lodgings at the Academy by a coach to a transport hub to the south of the city. The place was a clash of technological eras, with a cobbled road bearing horse-drawn traffic leading to a railway terminus, and splashes of scarred concrete where stood slim needles, kernel-driven ships of air and space.

‘You know, I realise now in fact that I’ve travelled little since I got here,’ Penny said as Marie helped her down from the coach. ‘Twenty years since the jonbar hinge brought us here, and I’ve barely left the city. I’ve spent more time off the planet than travelling on it, probably.’

Marie gave her an arm to lean on. ‘Well, why travel when you are immersed in strangeness every time you open your door?’

‘True, true.’

Marie was in her forties now, plump, greying, a mother of three; she still worked with Penny at the Academy, and in fact had long since taken over many of Penny’s administrative duties. Penny depended on Marie in many ways – and, she believed, Marie had found a reasonable happiness in her life here, with her husband Rajeev, even though they were all so far from home.

With servants from the Academy handling their luggage, they walked slowly to the railway terminus, a sprawling roof over multiple platforms, a tangle of lines spreading away in the distance. The architecture seemed very familiar to Penny; there was a certain inevitable economic and engineering logic to rail technology, it seemed. But Brikanti trains ran on gleaming monorails supported by elegant Roman-style viaducts, and their locomotives were powered by kernels, a handful of the mysterious wormholes in the heart of each engine. The train itself was a suspended tube of metal and glass. Penny was relieved to see there was an escalator to lift her up.

They had a carriage to themselves at the heart of the train, a roomy space centred on a broad table, brightly lit through big picture windows. It was almost like a dining room, Penny thought. Marie and Penny were in fact the last to arrive. Already here were Beth and Mardina, Beth looking resentful, and a rather more complex expression on Mardina’s face; she seemed uncertain, withdrawn. And here were Kerys and Ari Guthfrithson – Ari sitting a respectful distance away from his estranged wife and daughter.

Kerys stood to welcome Penny, and helped her get settled in her seat between Marie and Jiang, and called a servant to bring drinks. Kerys had been put in nominal charge of this peculiar mission, and if the nauarchus was irritated to be dragged once again into all this jonbar-hinge strangeness, she didn’t show it.