Havman’s studiously blank expression spoke volumes. He regarded the radar screen again. ‘We might be able to see it soon. There’s an opening in the ice.’ He pointed out an indentation in the fuzzy line.

Bekker went to the windows – and saw it for real. ‘It’s a cave!’

Havman followed his gaze with binoculars. ‘A big one.’

‘We could probably fit the whole ship inside.’

Chuckles from the bridge crew. ‘I don’t think that would be wise,’ said the captain. ‘We could send in the boat, though. If that’s what you want to do. It will cost us time.’

Bekker took his point. But the cave was tantalisingly close . . . ‘We need to see what it is,’ he decided. ‘We are doing a survey, after all. How long would it take?’

‘Thirty minutes, perhaps.’ Havman checked the water. ‘Not too much floating ice. We can bring the ship closer.’

Bekker tried not to sound too childishly enthusiastic. ‘Okay. Let’s do it. If it’s nothing, we’ll carry on with the survey.’

‘As you wish.’ The Swede adjusted the Dionysius’s course.

The ship soon drew level with the opening. Bekker tried to see inside, but all he could make out were twilight-blue walls of ice. He went back to the radar. The object should have been in line with the entrance. ‘I can’t see it.’

Havman rechecked the screen. ‘It must be embedded higher up.’

‘We’ll definitely have to take the boat in. Maybe we can climb up to it.’

The captain cocked an eyebrow. ‘We? Mr Bekker, do you have any experience in ice climbing?’

‘No, but—’

‘You’re my client, but you’re also my passenger, so your safety is my responsibility. You hired people who know what they’re doing. Let them go.’

‘I suppose you’re right,’ Bekker reluctantly agreed.

The Dionysius heaved to, crewmen preparing its boat for launch while Havman and Bekker spoke to the man and woman who would make the trip. Wim Stapper was a blond Dutchman with the wiry build of an extreme sports enthusiast, while the Finnish Sanna Onvaan had short, fiery red hair and the strong upper body of someone who spent much time dangling from high places. Both were in their late twenties and expert ice climbers. They were as enthusiastic as Bekker about the unexpected side mission. ‘If it is a UFO,’ said Onvaan, grinning, ‘maybe we get to take selfies with space aliens!’

‘We don’t know if it’s a UFO,’ said Bekker. ‘If it’s just a big rock, then we’ll carry on with the survey. But,’ a smile, ‘if it is a spaceship . . . get lots of pictures!’

Havman shook his head. ‘You have all seen too many movies. Don’t get too excited – that is when you make mistakes.’

‘We will be okay,’ Stapper assured him as he zipped up his red coat. ‘We know what we are doing.’