The killer came into view. He simply manifested out of nowhere, as if the air had parted like a curtain and let him through. He appeared high up on the span ahead of us, and began to plod down the steep slope. He did not see us at first. We heard his feet slapping heavily on the metal roadway.

Though humanoid, he wasn’t human. I was the largest man in our party, and he was twice my mass and half my height again. He came wrapped in a heavy, ragged cloak of animal skins with a hood drawn up. His shoulders were very broad.

The pain behind my eyes was getting worse by the second. I could barely focus.

‘Kill it,’ I said.

We opened fire: four military-grade autorifles, firing reinforced rounds with fifty per cent more grain in them than standard, Zelwyn’s lasgun, and my Tronsvasse assault pistol. The noise was stunning, and the muzzle flash a strobing flutter. The killer was dead in just a few seconds. Our firepower tore him apart and shredded his foul cloak, though he possessed such astonishing strength that he actually managed to walk into our fusilade a step or two, trying to shrug it off, before it overcame him.

He fell heavily, and rolled down the slope.

‘He’ was a mature ork warrior. Released by his spasming paws, a huge cleaver and a large metal cudgel lay on the roadway beside him. We approached slowly. Greenskins are notoriously hard to kill, and though we had blown this one wide open, I fired three more rounds into its skull to be on the safe side. Ichor, almost black in the dawn light, ran down the slope. The mangled corpse showed signs of body paint, tribal markings and lots of crude piercings and bangles. Fresh human ears were strung around its throat on a wire.

‘A greenskin?’ Zelwyn murmured. ‘But this isn’t green space. There haven’t been any orks in this sub for generations.’

‘It didn’t come from this sub,’ I said. I was finding it hard to speak or concentrate. The pain behind my eyes was even worse than before. It felt like a hot wire. ‘It came from whatever random site this regia occulta connects to. This beast went hunting one day, and ended up here. We’ll never know, I fancy, where… where…’

‘Inquisitor? Inquisitor Eisenhorn?’ I heard Zelwyn say. I felt his hand catch my arm. The pain behind my eyes had turned into full-blown psyk agony. I could barely stand, let alone speak.

And I really wanted to speak. I needed to. I needed to yell out, ‘It’s not over!’

The regia occulta was still open. While we had been standing there, gawping at the ork’s cadaver, a second one had walked in through the hidden way.