One breath was all it took, on a pollution-ruined world like Fornax. The Adeptus Mechanicus really didn't care what environmental disaster was the consequence of the advance of their devotion to the Machine God. They wouldn't have got away with it on the windswept island-colonies of Cadia.

The smell of burning flesh and Katsulas's vomit penetrated Vessig's own rebreather and made him gag. Through sheer force of will and the need for battle-readiness in their predicament, he managed to keep his morning's rations down.

'Can he make it any further?' Vessig asked.

'I don't know much further he can go without proper medical aid,' Malone, the squad's hastily-prepped stand-in medic, reported. 'His airway could become obstructed even more by the phlegm his body will naturally produce to counter the effects of the poison.'

'I'm all right.’ Katsulas wheezed and then broke into a coughing fit.

'No you're not, trooper.’ Vessig corrected him. 'Don't talk. Save your breath for getting out of this hell-hole.’

Vessig scoped the road ahead of them. Thick black smoke rolled in from stinking chemical fires burning inside a gutted structure ahead and to the left, obscuring his view. He was now no longer certain where the enemy were within the maze of the buildings. They needed to secure another position from which they could reconnoitre the surrounding structures and alleyways. Ahead of them, past the corpses of the zombie pack, fifty metres away the sheet metal walls of a manufactory shed rose above the surrounding ruins, apparently almost intact.

Reverting to hand signals, Vessig moved his men towards the structure, Hacker watching their backs as Malone and Palno between them practically carried Katsulas along the road, his arms slung over their shoulders. Dundas and Saul ducked behind the gargoyle-pillared columns at the open entrance to the shed, the door a buckled sheet of metal lying against a toppled Sentinel-lifter on the other side of the fer-rocrete roadway.

The industrial hangar enclosed an area of at least a square kilometre. The vast space was littered with the incompleted trackless hulls of tanks and armoured personnel carriers, although their armour plating had done little to protect them from the artillery bombardment the insurrectionists had subjected this area to.

Amazingly, most of the roof of the building was still intact. A large section was missing where a piece of masonry from another generarium had been thrown through the corrugated iron skin to land in the centre of the vast hangar, crushing a Consul-pattern tank chassis under its rockcrete mass.

'Ranpol and Dundas, stand guard by the door.’ Vessig commanded. 'Irving and Hacker, I want you to check out the rest of this place. I don't want us being surprised by anyone coming in through the back.’

The troopers jogged off into the gloom, passed the shells of tanks and troop carriers. Meanwhile Malone had dragged the still coughing Katsulas into the shelter of a Trojan hauler and had opened up a medi-pack to see if he could do anything more for the choking trooper.