'Geothermal must have gone up.’ said Shen as he scanned for targets. His inferno pistol was an exceedingly rare weapon that packed the power of a melta gun into a relatively small pistol, and at short ranges it could carve through anything. 'Without maintenance half the hive is probably ready to explode.'

Sister Mixu pointed up at a symbol, half a stylised metallic skull and half a square-toothed cog, grinning lopsidedly down from the mass of twisted metal. 'The symbol of the Mechanicus. Looks like we're close, sister.'

'Movement!' shouted one of the Seraphim. Sister Aescarion turned to see one of the Sisters opening fire into the shadows. Shen followed her aim, firing a bolt of superheated matter that briefly lit the twisted, sub-humanoid shapes that were massing in the gloom.

The enemy weren't bandits, because they didn't steal anything. It was as if they pounced on anything living just for the novelty of killing something alive. They were the shambling remnants of the underhivers who had been reduced to walking corpses by the plague, and they had dogged the heels of Shen and the Seraphim for whole hellish journey to the underside of Hive Quintus.

In the brief burst of light, Aescarion counted fifty plus of them. The inferno pistol claimed three, scorched to cinders, and bolt pistol fire stitched a bloody path through several others.

'Fall back!' called Aescarion and drew her Sisters around her, adding her bolt pistol fire to theirs. The hive-scum surrounded them, clambering from the ragged walls, moaning their death-rattles. She could see their peeling skin and the runny whites of their eyes, their lolling jaws and the gnarled, blackened fingers that held crude clubs and blades.

If there was proof that Eumenix was cursed by Chaos, it was this. A disease that not only killed, but turned the bodies of its victims into mindless predators to stalk the survivors.

The Seraphim backed off slowly, pumping bolts into the shambling wave of the dead that was pouring in ever-greater numbers into the cavity. Shen's inferno pistol was recharged and sent out another hissing lance of fire that tore through a dozen scum at once.

'We're surrounded.’ said Shen with a calm that struck Aescarion as most admirable. He indicated the Mechanicus symbol. We'll have to cut our way out. Head that way and we may hit the outpost, it'll be easier to defend.’

Aescarion nodded in agreement and drew the power axe from its holster on her back. She had fought with that same axe for decades, always refusing more refined weapons because the brutality of the axe was a befitting tool to bring down the Emperor's unflinching justice.

The weapon's blade hummed to life and a shimmering blue power field played around it.

'With me!' yelled Shen and fired his inferno pistol into the knot of plague-scum beneath the Mechan-icus symbol. He charged into the remainder, barging their rotting bodies aside. The Seraphim behind Shen blew bodies apart with their twin bolt pistols. Sister Aescarion ran past Shen into the underhivers, hacking at the wall of flesh in front of her. Gnarled hands reached towards her and she hacked them off with her axe, punching her gauntleted fist into the mutilated faces behind. She stamped down and felt bodies crunching beneath her feet. Bolt pistol fire raged past her into the plague-dead, thinning them out around her as she and Shen barged their way through their attackers and out of the explosion site.

They plunged deeper into the darkness, snapping off shots at anything that moved. At Shen's lead they kept moving, knowing that if they stopped, their slower but massively more numerous attackers would be able to surround them and cut them off in the narrow, twisting tunnels below.

Age-darkened brass and heavy gothic mechanical architecture began to surface amongst the grime of the underhive. Massive industrial cogs lay here and there and the symbols of the Machine-God were tooled into every girder. The Adeptus Ministorum were privately wary of the Adeptus Mechanicus -the tech-priests worshipped the Omnissiah, the Machine-God, which they claimed to be an aspect of Emperor, but the Ministorum had their secret doubts. That said, Sister Aescarion was grateful that at least they knew how to build.

The Mechanicus outpost was a solid cube of brass, its surface knotted with pipes, strong enough to survive the crushing weight of the hive above it. The entrances were massive blast doors sealed tight and Shen stepped back warily when he saw the sentry guns and the bullet-riddled bodies of plague-dead that had been unfortunate enough to shamble into range.

The squad scouted around the outpost, finding scores of dead - most of them infected but some in the rust-red coveralls of Mechanicus menials, along with one or two servitors hurriedly refitted for combat. Corpses lay draped over makeshift barricades, set up to funnel the shambling hordes into kill-zones now choked with their bodies. The outpost must have held out for weeks as Hive Quintus slowly turned into hell.

One door was not sealed. The underside of the outpost was blackened with scorch marks from a massive explosion that had ripped the lower hatch open, lagged metal ringed the opening overhead like torn skin around an open wound.

Shen waded through the knee-deep murky water that filled the tunnels beneath the outpost. The opening overhead was dark and the walls were riddled with bullet holes.

'Bolter fire,' said Aescarion. She had seen the results of bolter weapons more often than she could remember. 'Disciplined. Tightly grouped.’

The final reports off Hive Quintus had been of the last shuttle out being stolen by purple-armoured monsters, leaving the wealthy Cartel Polios on the hive to die. Shen and Aescarion had been sent to find out if there was any truth to them, but the outpost was the only place on the planet where Imperial personnel might survive to verify them. Now it seemed that not only had the outpost fallen, but that the Soul Drinkers might have been the ones who attacked it.

Shen reached up and grabbed the edge of the wrecked blast door above him. He hauled himself up through the opening and switched on the light mounted on the collar of his armour.

'Nothing.’ he said. There must have been a hell of a firefight here. Small arms and grenades. There are bodies everywhere.’

'Follow me.’ said Aescarion to her Seraphim, then followed Shen into the body of the outpost. She was reminded of her age as she clambered up beside him - it would have been much easier with the jump packs Seraphim usually fought with, but they had left the packs behind since a hive city was hardly the most appropriate terrain for their use.

Shen was right. The straight, metal-walled corridors of the outpost had seen ferocious fighting. Blade marks on the floor and walls told of hand-to-hand butchery, the bullet-riddled walls of massive weight of fire. The corpses of menials lay where they had fallen defending the breached entrance.

The rest of the Seraphim climbed up into the corridor. 'No life signs.’ said Sister Mixu, who carried the squad's auspex scanner. 'But there's a lot of interference. This place is pretty solidly built.’

The underhivers didn't do this.’ said Shen.’ And if the Soul Drinkers didn't then it was somebody capable of bringing down a similar level of firepower. We need to find out what they wanted with this place.’

Agreed.’ said Aescarion. 'Could the Mechanicus have been working on something here? A weapon?'

'We'll find out. This outpost will be built along standard template construct lines. There'll be a control post at the centre and a testing bay not far above us. We'll try those first, then scour the rest.’

The outpost was a combination of massive industrial workings and the sort of oppressive gothic architecture that Aescarion was familiar with from the convent prioris on Terra. Fluted columns separated banks of cogs like giant clockwork, frozen by the outpost's shutdown. Turbines lay beneath vaulted ceilings. Shrines to the Machine-God were everywhere, stained with libations of machine oil, scrawled with prayers in binary. Everything the Mechanicus did needed the correct rites enacted to the Machine-God - and judging by the abundance of offerings and prayer-tablets in the empty armoury, it seemed that included fighting.