Nina stared at the Nephilim with renewed astonishment. He was over five hundred years old – and had stepped out of the past after more than one hundred thousand years as if not a day had passed. The technology, if something that used crystals and stones rather than gears and circuitry could be so described, of the Veteres and their Nephilim cousins was far beyond anything previously known. ‘So you chased the Veteres to Antarctica?’

Gadreel’s face darkened. ‘Yes. We knew they would hide where the lines of qi were strongest.’ Zan put the translation into terms with which he was familiar. ‘My priestesses followed the lines. But we went into a night that did not end, with a terrible storm. We could not go on.’

An Antarctic winter, Nina realised; for all their advances, the ancient race would probably have been unaware that the continent was plunged into darkness for part of the year. ‘So you put yourselves into the sarcophagi?’

‘Yes. Our supplies ran low. Only a priestess can put us to sleep, or wake us. One chose to remain, to wake us when the storm passed and the sun returned.’ A flicker of sadness. ‘She must not have lived.’

‘I’m sorry,’ Nina said. ‘Was she one of your family?’

‘My people are all my family – I don’t think he means in a literal way,’ Zan interjected, before continuing to translate. ‘But my wife and son were safe; they were sleeping in another place. Before I left, I hid the rest of my people to wait for our return.’

‘But you never did return. So – they might still be there, still sleeping.’

‘Yes . . .’ He straightened, suddenly hopeful. ‘If I help you find them . . . will you help me wake them?’

‘I’ll do what I can, yes. Are they in another fortress?’

‘Yes. It is bigger than the one in which you found me.’

Nina glanced up at the cameras. Gadreel had just confirmed he knew where the main fortress was buried – but that triggered a different thought. She turned back to Zan. ‘The word we’re using, fortress – that’s definitely the correct translation?’

He prickled as if she were accusing him of making a mistake. ‘Yes, of course!’

‘It’s okay, I’m not saying you’re wrong. But a fortress is a fixed defensive structure – yet the Nephilim travelled across Antarctica, and an ocean before that, until theirs got trapped in the ice . . .’ She faced Gadreel through the glass. ‘Your fortress – how did you get it to Antarctica?’

Gadreel looked back – then, just for an instant, his gaze flicked away before he spoke. ‘How would you cross a sea?’

‘By boat?’ Nina replied, suddenly suspicious. Was he dissembling, hiding something?

‘Yes, by boat,’ came the reply. ‘That is how we travelled there.’

‘That’s not what I asked.’ But before she could press him further, the laboratory’s main door opened, and Colonel Wu and his escort entered.