The denial of reinforcements was a bitter blow, and Kadai had been incensed at the news. But the granite-hard pragmatist in him, the Salamanders spirit of self-reliance and self-sacrifice, proved the stronger and so he had put his mind to the task at hand using the forces he did possess. In response to the casualties, Kadai had combined the three groups of Devastators into two squads under Lok and Omkar, Ul’shan with his injury deferring to the other two sergeants. Without reinforcements, the Tactical squads would simply have to soak up their losses.

‘With Fugis gone, I’m reluctant to risk more of our battle-brothers heading into the unknown,’ Kadai said, the shadows in his face making him look haunted. ‘The heretics are entrenched and well-armed. We are few. This would present little impediment should we have the use of our flamers, but we do not.’

‘Is there a way to purify the atmosphere?’ asked N’keln. He wheezed from a chest wound he’d sustained during the withdrawal to Aereon Square. N’keln was a solid, dependable warrior, but leader-ship did not come easily to him and he lacked the guile for higher command. Still, his bravery had been proven time and again, and was above reproach. It was an obvious but necessary question.

Brother Argos stepped forward into the reflected light of the schematic.

The Techmarine went unhooded. The left portion of his face was framed with a steel plate, the snarling image of a salamander seared into it as an honour marking. Burn scars from the brander-priests wreathed his skin in whorls and bands. A bionic eye gleamed coldly in contrast to the burning red of his own. Forked plugs bulged from a glabrous scalp like steel tumours, and wires snaked around the side of his neck and fed into his nose.

When he spoke, his voice was deep and metallic.

‘The hydrogen emissions being controlled by Cirrion’s atmospheric processors are a gaseous amalgam used to inflate the Stratosan dirigibles – a less volatile compound, and the reason why bolters are still functioning normally. Though I have managed to access some of the city’s internal systems, the processors are beyond my knowledge to affect. It would require a local engineer, someone who maintained the system originally. Unfortunately, there is simply no way to find anyone with the proper skills, either alive amongst the survivors or amongst those still trapped in the city.’ Argos paused. ‘I am sorry, brothers, but any use of incendiary weapons in the city at this time would be catastrophic.’

‘One thing is certain,’ Kadai continued, ‘the appearance of civilian survivors effectively prevents any massed assault. I won’t jeopardise innocent lives needlessly.’

Tsu’gan shook his head.

‘Brother-captain, with respect, if we do not act the collateral damage will be much worse. Our only recourse is to lead a single full-strength force into Cirrion, and sack it. The insurgents will not expect such a bold move.’