Honsou laughed as he watched the dreadnoughts and the thousands of enemy soldiers below turn to flee the avalanche, knowing that they were already doomed. The tide of rock swept over them all, pouring down the slopes they had fought and bled to capture.

The rumble of grinding rock slowly faded, as did the bellowing roar of the guns, Berossus realising that their fire would be wasted without an escalade.

Honsou turned from the mass destruction he had unleashed.

Now Berossus would know he had a fight on his hands.

The unchanging sky and static sun made it impossible to discern the passage of time through their surroundings, and the internal chronometer on Uriel's visor had only displayed a constantly fluctuating readout that he eventually disabled. Days must surely have passed, but how many was a mystery. He had heard that time flowed differently in the Eye of Terror, and supposed he should not have been surprised at such affronts to the laws of nature.

'Emperor, I hate this place,' said Pasanius, picking his way over a pile of twisted iron jutting from the rock of the mountain. 'There is not one natural thing here.'

'No,' agreed Uriel, tired and hungry despite his armour's best efforts at filtering and recycling his bodily excretions into drinkable water and nutrient pastes. 'It is a wasteland of death. Nothing could live here.'

'I think something lives out here,' said Pasanius, glancing at the darkened peaks all about them. 'I'm just not sure what or that I even want to find out.'

'What are you talking about?'

'Haven't you felt it? That we're being watched? Followed.'

'No,' said Uriel, ashamed that his instinct for danger appeared to have deserted him. 'Have you seen anything?'

Pasanius shook his head. 'Nothing for sure, no, but I keep thinking I can see, I don't know, something.'

'Something? What kind of something?'

'I'm not sure, it's like a whisper in the corner of my mind's eye, something that vanishes as soon as I try to look at it,' said Pasanius, darkly. 'Something red…'

'It is this place,' said Uriel. 'The lair of the Enemy will attempt to mislead and betray your senses. We must be strong in our faith and resist its evil magicks.'

Pasanius shook his head. 'No, it is something not of the Enemy, but something that lives here. I think it's what killed those people in the cave.'

'Whatever killed and skinned those people was evil and an enemy of all living things. Let them come, whatever they are, they will find only death.'

'Aye,' agreed Pasanius as they climbed onwards. 'Death.'

The besieged fortress was lost to sight for now, the path from the tunnels leading them down into the rocky gullies and crevasses of the mountains. The white sky beat down upon them, harsher than the fiercest sun, and Uriel deliberately kept his eyes averted from its flat emptiness. Once, he thought he caught a glimpse of the red things Pasanius claimed were following them, but they defied his every attempt to see them properly. Eventually he gave up, unable to catch sight of them, and concentrated on simply putting one foot in front of the other.

The harsh, metallic shale of the mountainside grated beneath his boots and every now and then they saw grilled vents piercing the rock that disgorged a hot steam that tasted of beaten metal. The vents plunged down into the mountain, the darkness impenetrable, even to a Space Marine's enhanced eyesight.

Uriel saw billowing smoke stacks hundreds of metres above them, thousands of blocky chimneys lining the ridge like great pylons that spewed corrosive fumes into the atmosphere. Yet no matter how much black waste was released into the air, the dead sky was always above them, blank and oppressive.

Over the tops of the mountains before them, Uriel could see what looked like bloated dirigibles, drifting above somewhere ahead in the mountains. Long cables drooped from their bellies, but whether these were simply anchoring them to the ground or acting as some form of barrage balloon, Uriel could not tell. Perhaps they were designed to keep the delirium spectres at bay from some facility as yet unseen?

As their weary trudge through the reeking air of the mountains continued, the two Space Marines passed a shorn quarry of shattered stone, where the side of one of these Cyclopean smoke stacks was exposed. Reddish-brown stains spilled from the joints between the massive, curved blocks making up the stack and a monstrous heat radiated from the stonework in pulsing waves.

'Where do you think it goes?' said Uriel.

'I don't know. Perhaps there is some manufactory below the mountains.'

Uriel nodded, wondering what diabolical production line was at work beneath their very feet. Were men and women dying even now to forge weapons, armour and materiel for the dread legions of Chaos? It galled him that he could do nothing to prevent such abomination, but what choice did they have? The sacred task of the death oath placed upon them by Marneus Cal-gar took precedence over all other concerns. The daemonic womb creatures… these daemonculaba were in the besieged fortress they had seen as they climbed from the darkness of the tunnels beneath the mountains and nothing would stand in Uriel's way of reaching that damned place.

Pressing on, Uriel and Pasanius climbed a jagged, saw-toothed ridge, its sides sheer and corrugated, as though gouged by some gargantuan bulldozer blade. A blackened depression of splintered stone and iron, thousands of metres in diameter, fell away from them on the other side, crags of iron columns and twisted girders protruding from the mountain like clawed fingers. The depression appeared to be perfectly circular, though it was difficult to tell, whipping particles of sand and iron filings filling the air and lashing round the circular valley in spiteful, howling vortices. A narrow sliver of white sky was just visible on the far side of the depression, but all Uriel's attention was fixed on the sight that filled the centre of the depression.

'In the name of the Emperor…' breathed Uriel in disgust.

A huge grilled platform filled the centre of the depression. Agglomerated layers of dust coated its every surface and its perforated floor dripped and dogged with jelly-like runnels of fat and viscera. Tall poles jutted from the platform, held in place by quivering steel guys that sang as the unnatural wind whistled through them. Hooked between the poles were billowing sails of flesh, stretched across timber frames that the scouring, wind-borne particles might strip them of the leavings of their former owners.

Monstrous, debased creatures in vulcanised rubber masks with rounded glass eye sockets and ribbed piping running into tanks carried on their backs scraped at the stretched skins with long, bladed polearms. They lurched across the platform with a twisted, mutated gait and gurgled monotone commands to one another.

'What are they doing?' said Pasanius, horrified at the sight before him.

'It looks like they're curing the hides, scraping them clean,' said Uriel.

'But the hides of what?' said Pasanius. 'They can't be human, they're too large.'

'I don't care what they are,' snarled Uriel, setting off down the treacherous slope towards the platform and drawing his golden-hilted sword. 'This ends now.'

Pasanius set off after Uriel, unlimbering his flamer and checking its fuel load.

If the mutant creatures were aware of them they gave no sign, the howling wind and rumble of distant artillery masking the sounds of their approach. But whatever they lacked for in awareness, they made up for in thorough diligence, dragging their bladed polearms up and down the length of the billowing skins to clear them of whatever the lashing winds left behind. Uriel saw a carven set of stone stairs leading to the platform and took them two at a time as his anger continued to build.