‘In the UFO.’ Two faces peered down fearfully from the hatch. Eddie waved to them. ‘We’re okay!’ he called. ‘Use the ropes to climb down to us.’

‘I need to get back into the fortress,’ said Nina.

A moment of silence, then: ‘You what?’

‘I think I started all this when I touched the key after Cheng put it in the altar – so maybe I can stop it as well! Like in the vault in Turkey – I felt as if I could control the flow of earth energy. If I can do the same here—’

‘This whole place’ll come apart before you get the chance!’ Eddie countered. Even though the fortress was approaching equilibrium, the iceberg around it was still racked with tremors, as if D43 was fighting back against whatever unnatural forces had rolled it around. Deep, dark cracks now sliced through the translucent sapphire ceiling, and the water’s surface was alive with splashes as ice constantly fell from above. ‘Wait here – I’ll see if there’s a lifeboat we can use to get out.’

He turned – and to his dismay saw a frost-shrouded orange fibreglass hull mangled beneath the fallen crane. ‘Buggeration and fuckery! What are the bloody odds?’

Wait – the ship itself was still afloat . . .

A couple of life vests hung on hooks beside the crushed lifeboat. He looked up at the ledge. Imka had attached another length of rope to the carabiners and thrown it down the slope. ‘Grab these and get onto the ship!’ he shouted, before tossing both vests ashore.

‘Shouldn’t we swim out of the cave?’ Imka yelled back.

‘Only if you want to be stuck on a freezing iceberg with no food and no shelter! You know how ship engines work, don’t you?’

‘Yes, but—’

‘If you can start this one, we’ve got a chance of staying alive!’

Imka seemed unconvinced, but nevertheless started down the slope.

Nina regarded him with equal disbelief. ‘This ship’s been frozen upside down for four months, and just got dropped from the ceiling! We’re lucky it hasn’t sunk already – I don’t think we’ll be able to just push the starter and chug out of here.’

‘It’s a big diesel engine – it takes a lot to fuck ’em up. And the fuel’ll have loads of antifreeze in it. As long as it hasn’t all leaked out, we might be able to get the ship running – if we can start it.’

‘That’s kind of a big if.’

‘I’d rather try it than swim outside and climb the iceberg. Especially when Harhund’s still out there.’ That triggered a mental warning: where was the mercenary leader, and what was he doing? ‘Keep moving, it’ll help you warm up. I’ll be right back.’

He hurried to the stern. The cave mouth was an irregular oval of glare. He squinted, trying to focus on what lay beyond.