‘We will,’ Nina assured her. ‘But we have to check the rest of the fortress first. There might still be survivors.’ She didn’t believe her own words, but Imka was desperate enough to cling to the tiny chance that she nodded.

The group helped Eddie back up, and they returned to the entrance. The demonic armour watched from its icy prison as they passed. ‘Same drill,’ said the Yorkshireman. ‘Hold the rope, help me down, and I’ll see what’s there.’

‘Be careful,’ said Nina as he started his descent.

‘Oh, I bloody will be, don’t worry!

He held up his light as he moved down the slope, wishing he could exchange it for a gun. Stapper’s story was looking less like the result of his madness and more like the cause. Something had killed two people in a truly horrific manner, enough to unsettle even a man who had seen every form of death imaginable.

And whatever had done it was still here, somewhere in the frozen darkness.

No sign of more bodies – or their splattered remnants – but before long his descent brought him to something else. ‘There’s some stairs here!’ he shouted. They led to the higher deck. ‘I’m going up.’

‘What can you see?’ Nina called after him as he ascended.

The low blue light of the ice cave surrounded him, coming through two elongated windows; the ‘dragon eyes’ they had seen from outside. One was broken, cold air wafting in. ‘It’s a big room,’ he said. ‘High ceiling, like a dome.’

He stopped at the top of the stairs, sweeping the light around. The room was oval, a large metal dais towards the rear. The underside of the egg-shaped object inset into the top of the ship rested upon it; it was a separate entity. Its nature and purpose remained a mystery, though.

Before it sat something he could identify – an ornate golden throne. Like the armour, it was on a considerably larger scale than human. ‘It’s a throne room!’ he shouted. ‘Nobody here, not that I can see. I’m going to look around.’

He moved cautiously into the steeply sloping chamber to continue his search for bodies, soles squeaking faintly on the floor. At its centre stood a large rectangular plinth. An altar? He headed towards it. His light picked out a recess set into its top.

He recognised the shape. The space was a perfect match for the key Krämer had stolen.

The realisation put him back on full alert. He turned to scan the whole room, shining the powerful beam into the shadows of the crystal pillars. Nothing there, no movement. Not reassured, he reached the altar. The upper surface was orichalcum and the same dark, oily metal as the hull, inset with numerous concentric circles of crystal and purple stone.