Another giant wearing the red-scaled plate came forward. Tendrils of smoke emanated from the grille in his horned helmet. The silence of the outer vault was broken by the hissing, crackling intake of breath before the horned one unleashed a furious plume of flame. It surged hungrily through the grille-plate in a roar, smashing against the vault door and devouring it.

Reinforced plasteel bars blackened and corroded in seconds, layers of ablative ceramite melted away before the adamantium plate of the door itself glowed white-hot and sloughed into molten slag.

The warriors had travelled swiftly through the mag-tram tunnel, forging deep into the lesser known corridors of Cirrion. None had seen them approach. Their leader had made certain that the earlier massacre left no witnesses. After almost an hour, they had reached their destination. Here, in the catacombs of the city, the hydrogen gas clouds could not penetrate. They were far from the fighting; the battles going on in the distant districts of Cirrion sounded dull and faraway through many layers of rockcrete and metal.

‘Is it here?’ asked a third warrior as the ragged portal into the vault cooled, his voice like crackling magma. Inside were hundreds of tiny strongboxes, held here for the aristocracy of Stratos so they could secure that which they held most precious. No one could have known of the artefact that dwelled innocuously in one of those boxes. Even upon seeing it, few would have realised its significance, the terrible destructive forces it could unleash.

‘Oh yes…’ replied the eldritch warrior, closing crimson-lidded eyes as he drew upon his power. ‘It is exactly where he said it would be.’

Desperate and dishevelled, the Stratosan masses tramped into Aereon Square.

Most wore little more than rags, the scraps of whatever clothed them when the cultists had taken over the city. Some clutched the tattered remnants of scorched belongings, the last vestiges of whatever life they once had in Cirrion now little more than ashen remains. Many had strips of dirty cloth or ragged scarves tied around their noses and mouths to keep out the worst of the suffocating hydrogen gas. A few wore battered respirators, and shared them with others; small groups taking turns with the rebreather cups. The hydrogen had no such ill-effects on the Salamanders, their Astartes multi-lung and oolitic kidney acting in concert to portion off and siphon out any toxins, thus enabling them to breathe normally.

‘An entire city paralysed by terror…’ said Ba’ken as another piece of shrapnel was removed from his face.

The burly Salamander was sat up against the perimeter wall, and being tended to by Brother Emek who had some rudimentary knowledge of field surgery. Ba’ken’s battle-helm had all but shattered in the explosion that destroyed his beloved heavy flamer and, after being propelled through the wall, fragments of it were still embedded in his flesh.