She hurriedly regained her hold on the wheel and spun it. The ship swung away from a solid collision, but not quickly enough to avoid a glancing one. It caught the ice in a series of stuttering blows, scattering the deck with frozen debris before finally pulling free.

But they were still inside the passage, open sea more than a ship-length away – and the ceiling kept dropping like a car crusher. The brightening daylight dimmed again, blotted out by a solid sapphire-blue firmament—

A thunderous roar came from behind, from above, even below – and the new sky split apart.

Icy meteorites bombarded the Dionysius as D43 tore asunder, cleaving along a line directly through the spot where the fortress had been trapped. The two halves peeled apart, the ship no longer in a tunnel but at the bottom of a widening chasm. Massive waves rushed down the channel, snatching up the battered ship and flinging it towards the open sea.

The diesel died as it was swamped by tons of water rushing down the stub of the funnel. More sluiced in through the broken windows, the bridge’s occupants taking another soaking. But they were concerned only about holding on as the vessel pitched and rolled. Nina hooked one arm around a handrail, clinging to Eddie as they were flung back and forth over the wet deck . . .

Then the wild ride eased.

Nina shook wet hair off her face. ‘Is everyone okay?’ she gasped.

‘Feel like the pea in a bloody whistle,’ Eddie spluttered, ‘but yeah.’ He staggered upright. ‘Imka! Cheng!’

Cheng had wedged himself between the bridge wall and a console, clutching his backpack. ‘I’m . . . okay. I think.’

‘So am I,’ said Imka blearily as she slumped over the helm – only to gasp as she took in the view.

Nina had much the same reaction. Surrealistic spires and arches had risen from the sea, lancing almost horizontally from the iceberg’s body. One half of D43 had rolled by nearly ninety degrees, submerged features brought spectacularly into the light. The other, larger part of the iceberg had not made such an extreme shift, but was still a good twenty degrees off its original alignment, newly exposed strata shimmering as water streamed down them.

The cavern was gone – as were the remains of the fortress. Everything they had discovered was now on its way to the bottom of the Southern Ocean. All that survived was the coffin the mercenaries had stolen, and the key inside the pouch on Nina’s chest.

Eddie took in the incredible sight, but quickly moved past astonishment to concern. ‘Where’s the other ship?’ His view was restricted by the walls of the newly formed fjord, and there was no sign of Harhund’s vessel.

‘Maybe it got squished when the berg rolled,’ Nina suggested hopefully.