'Were there not four swarms approaching us earlier?' he asked.

'Yes, Captain Ventris,' nodded Rabelaq, 'but we believe that the smaller northern swarm has simply merged with the one moving in from Parmenis. They were, after all, less than thirty kilometres apart.'

'Are you sure about that?' asked Uriel.

'Well, no, but where else could they be? The northern mountains are impenetrable, Fabricator Montante has assured me.'

'With all due respect to Fabricator Montante, he is not a soldier. Can we trust our security to the conclusions of a logistician?'

'He has local knowledge, Captain Ventris. Major Satria concurred also and having seen hololithic topography of the region in question, I am in agreement.'

Uriel could see the others around the room were alarmed at the prospect of a potentially missing swarm, but since there was no proof as to its existence, none had any answer as to what could be done about it.

'How long do we have before they reach us?' asked Bannon.

'Five, maybe six hours at most,' said Rabelaq.

'Then let's get to work,' said Stagler.

Snow swirled in obscuring blizzards around the crumbling hab units of District Secundus, gathering in windblown drifts and deadening the sounds of the column of refugees that trudged through the knee deep white carpet that enveloped Erebus.

Displaced by the rain of organic bombs and those creatures whose cocoon spores were able to penetrate the flak umbrella protecting the city, nearly six hundred people trudged through the blizzard towards a nondescript collection of buildings constructed against the rocky sides of the southern slopes.

Armed men stood watch at the splintered timbers barring the entrance and a ragged tarpaulin flapped behind them.

Since the first days of the tyranid attack, word had spread of the hero Snowdog who had saved the people of the Secundus hanties from the tide of alien beasts that dropped from the skies. That his reputation as a murderer and thief were well known was secondary to the fact that people said he had food and medical supplies.

The winters of Tarsis Ultra were harsh and those without wealth or dwellings would soon perish without shelter.

And there was a brutal killer on the loose somewhere in Erebus.

Even amid the chaos of an alien invasion, its depredations could not go unnoticed: small, isolated groups of citizens found butchered like livestock, their bodies hacked to pieces and their flesh devoured. Fear whipped through the poorest quarters of the city, and those that could not escape to the high valley, where the soldiers of the Fabricator Marshal patrolled the streets and thoroughfares where the monied citizens of Erebus dwelled, were forced to band together for mutual protection.

As the fear of this mysterious butcher grew, so too did its violence, as though the very terror it spawned drove it to new heights of slaughter. Whole communities were murdered in their homes and only the ruthlessly patrolled area around the territory of the Nightcrawlers seemed to escape the killer's attention.

For people with no hope, Snowdog was their only hope.

Papa Gallo, the unofficial but acknowledged leader of the group, pulled back his hood and approached the two men guarding the door. The shorter of the pair racked his shotgun and jammed it in his face.

'We've come for shelter from the monsters,' explained Papa Gallo.

'Shelter's not cheap,' came the muffled reply.

Pappa Gallo laughed, turning to face the wretched people behind him. 'Look at us. What do you think we can offer you? We don't have anything left.'

'Oh, I don't know,' laughed the other man, eyeing the younger women. 'What do you say, Lomax? I bet we could come to some arrangement with these good people.'

'Shut up, Trask,' said the man who had spoken first. 'That's for Snowdog to decide.'

Pappa Gallo sighed. They might live through this winter, but if they did, they would emerge more desperate than before.

Deep in the shadows of the rained habs, crouched beneath a buckled sheet of corrugated iron, a creature watched the column of refugees through multi-faceted eyes, scenting the fear and despair as coloured washes through its various senses. Its flesh rippled a silvery grey as its chameleonic scales mirrored the surfaces around it and, with a stealth surprising for such a large creature, it slipped away from its shelter.

Its reserves of fatty tissue were low and it would need to kill again to replenish them, the freezing temperatures of Tarsis Ultra almost too much for even its fearsome adaptive qualities to cope with.

Since its virtual hibernation in the grain silos of Prandium, the beast, a species known by Imperial troops as a spook or mantis stalker, but more correctly as a lictor, smoothly loped across the snow to shadow the shambling people. It leapt onto the wall of a crumbling brick building, powerful intercostal muscles lashing fleshy barbs towards the top of the wall, which retracted to pull the beast rapidly up the sheer surface.

Long scythe-like claws unsheathed from chitinous hoods on its upper arms and dug into the wall as it smoothly swung its muscled bulk onto the roof.

Worm-like tendrils surrounding its jaw scented the air, and the beast set off again, following the column of refugees from on high.

Pheromone sacs situated along the ridge of its armoured spine atomised powerful attractants that would serve to lure more tyranid creatures to this place. Thus far it had roamed the city unmolested, careful to avoid the many dangers in such a heavily populated place.

But now the overmind, for whom it had travelled far ahead, was upon this place and it could afford to throw off its stealthy mantle and kill with all the ferocity it had been bred for.

The lictor stalked to the edge of the roof, squatting on its haunches as it watched a figure detach from the column and approach a building that stank of prey.

Trask let Lomax do the talking as his eyes roamed over the women, though it was hard to spot the lookers thanks to the winter clothing most were wearing. He rested his shotgun on his shoulder and wondered again how the hell Snowdog had managed to pull one over on all these people. One moment of foolish altruism had spread the word throughout the city that he was running some kind of refuge from the cold and the aliens.

It made Trask want to laugh fit to burst at the thought of how wrong people could be. Those that had been allowed to stay were paying through the nose for everything they needed: shelter, food and even basic medical supplies. Some wanted narcotics, an escape from the terror, and that was available too. Also at a price. And if someone couldn't pay with hard currency or in valuables, then there were always other ways. A man with a comely wife or daughter could obtain things a single man could not, and amongst Snowdog's gang, there were plenty willing to accept that currency.

Snowdog had put a stop to that because it didn't bring any profit, which hadn't stopped Trask of course, he'd just had to become more circumspect.

In a group this size there was sure to be some money to be made and a few fillies to pluck. As he was contemplating the prospect of fresh conquests, a blur of motion caught his eye atop the smashed ruins of the old munitions factory. He raised a hand, squinting against the glare and through the flurries of snow.

What the hell was that?

He couldn't see anything now, but he was sure his eyes weren't playing tricks on him.

There! There it was again! Something dropped from the roof of the building, landing in a snowdrift with a piercing shriek. Whatever it was, it moved like quicksilver, charging into the mass of refugees before he could shout a warning. He brought his shotgun down and racked the slide as the screaming began.