Cheng had by now huffed and puffed his way up the ladder. As Nina stepped onto the hull to make room for him, the interference became audibly worse. ‘Can you still hear me?’ she asked.

‘Just about,’ Tate replied through the distortion. ‘There’s some really bad static. You standing next to a generator or something?’

‘Something,’ Nina echoed. ‘Keep talking, I want to check this.’

‘Keep talking? Sure, what about? I could tell you about the cricket, I supp—’

She stepped through the oval hatchway – and the moment she crossed the threshold, Tate was cut off. Back outside, and his voice returned. ‘—fifty runs!’

‘Okay, thanks,’ she said, before calling down to her husband. ‘Eddie! This thing blocks the radio! Someone might need to stay outside so we can keep in contact with the Torrox.’

Eddie had just helped Vorster onto the ledge; he looked between him and Imka. ‘Any volunteers?’

‘I’ve got to find out what happened to Arnold and the others,’ Imka insisted. The shipowner expressed a similar sentiment.

‘Either me or Marc, then – and as much as I’d like to chill out, there’s no way I’m letting you wander around an alien spaceship on your own,’ the Englishman told Nina. A glance at the approaching crewman. ‘I’ll break the news to him.’ He took back the radio and descended.

Nina peered into the opening again, Cheng using his own torch to illuminate the interior. He muttered something in Chinese. ‘What?’ she asked.

‘It’s the same metal. The hull and the door,’ he clarified with unexpected emphasis, indicating the dark material. ‘But it is different inside.’

‘Orichalcum,’ said Nina, aiming her beam at one wall. Panels of the red-tinted gold alloy shone back at her. Like the outer hull, there was a surprising lack of frost.

She leaned through the hatchway, after her experience with the radio now hesitant about setting foot inside. The light picked out something else protruding between the orichalcum panels. She thought at first it was ice, but then realised it was something altogether more unusual. ‘It’s crystal.’

Cheng looked for himself. ‘Is it broken?’

‘I . . . don’t think so.’

She was distracted from his odd question by the arrival of the South Africans. Imka stared through the entrance with concern. ‘Arnold!’ she shouted. ‘Arnold, it’s Imka! Is anyone there?’

Only echoes reached them. ‘I haven’t seen anything yet,’ said Nina. ‘But this thing is big – someone might have gone deep inside to protect themselves from the cold.’ It was a very long shot, and she was certain Imka knew it, but her companion was still clinging to any crumb of hope she could find.

Vorster’s eyes went to the walls. ‘That looks like gold!’

‘It’s orichalcum – an Atlantean gold alloy,’ Nina told him.

His eyes narrowed calculatingly. ‘You know . . . under the law of finds, this thing is ours! We’re in international waters, so anything we discover here belongs to us.’