‘Hope you mopped it up,’ said Eddie with a smile hardly brimming in sympathy.

The ship continued on. After twenty minutes, Tate leaned closer to the radar screen. ‘I think we’ve got something!’

The iceberg was now a ragged sweep across the screen’s right, still fuzzy as the radar return bounced off different layers of ice, but a harder shape beyond its boundary had come into view. ‘Is it the Dionysius?’ asked Imka.

‘Can’t tell,’ Tate replied. ‘Might be two things close together; almost looks like they’re overlapping.’

‘Take us in closer,’ ordered Vorster.

The captain turned the Torrox towards the iceberg. Everyone else went to the windows to gaze at the frozen cliffs. Even Cheng left his computer, transfixed. ‘It is beautiful!’

Nina could only partially agree. In terms of colour alone, it was spectacular. The ice ran in stunningly vivid strata of white and turquoise and cyan, their steep angle confirming that D43 had indeed rolled over. It had shed some of its bulk, but was still over a mile and a half long. But the iceberg itself was only beautiful in the same manner as a painting by Francis Bacon or H. R. Giger, something dredged up from the darkest depths of the subconscious. Pillars of glossy ice resembling melting candles rose skyscraper-high above the water, leaning at impossible angles or merging together in unsettling primordial conjugations.

And according to Stapper, there was something even more bizarre inside. She turned her attention back to the radar. Tate was right: there did indeed seem to be two distinct objects within the frozen wall, but like the ice pillars, they were blended into each other, the radar struggling to differentiate them.

As for what they were, she couldn’t tell. Neither looked like a ship – or a spaceship, for that matter . . .

Vorster still had the binoculars, staring intently at the base of the cliffs. ‘I think . . . Yes! I can see an opening!’

‘Big enough for a ship?’ Imka asked hopefully.

‘No, but . . . it goes into a cave. I can see waves inside.’

Nina and Eddie searched for what Vorster had seen. It was revealed as a low, dark mouth in the wall. ‘Definitely too small for a ship,’ said the Yorkshireman. ‘If that’s where the other one went in, it must be a lot bigger under the water. Good job it stayed at sea level when the iceberg rolled, or we’d never have seen it.’

‘Yeah, lucky break,’ said Nina, faintly puzzled. The topography visible in the picture sent to Imka was now part of the nine-tenths of the berg hidden beneath the ocean’s surface, but if the odd radar return really was the Dionysius, then it was still roughly at sea level. The iceberg hadn’t simply flipped over, but had rotated around an axis that somehow kept the cave containing the ship at the surface. She couldn’t wrap her head around the complexities of motion that would have required.