Eaten alive by flies. It was no way for a gladiator son to perish. He had not survived a bitter climb to maturity on Bodt, endured brutal warfare on Susa and Sha’Zik and the breaking of his own oaths just to die unremarked in a plasteel tunnel, surrounded by wailing humans. He would keep firing the guns, then. He decided this as the overload warning icons on their grips flashed crimson. Yes. Keep firing until the weapons in his hands exploded. Volkite flame would consume everything.

‘It’s… all one mind,’ Varren heard the psyker mutter. ‘A single swarm-consciousness…’

‘Then we’ll die killing it!’ he shouted, and opened fire again.

‘Not today, brother.’ The words came over the vox. ‘Look sharp!’

Across the corridor, where the metal wall became the outermost hull of the Walking City’s construction, a shimmering sword blade burst through the steel with a howling screech. Thick yellow sparks flew as the blade cut a molten-edged ‘V’, and then the weapon withdrew.

Ison was already herding the surviving civilians back towards the rent in the wall, as ceramite-clad fingers wrenched at the glowing cut and pulled the metal back from the outside, as if flaying the pelt from an animal.

A gust of icy cold air blasted in through the tear in the hull and Varren saw a figure silhouetted there – a legionary in grey with a smoking sword in one hand, and about his head, an armour cuirass detailed with a brass Imperial aquila. ‘Get them out!’ shouted Nathaniel Garro, wrenching a melta bomb from a hook on his belt.

A wild laugh burst from Varren’s mouth and he drew back, still firing, ignoring the burning pain through his gauntlets. The swarm wavered, as if the mass of insects sensed what was about to happen. He was the last through the rip in the hull and as he passed Garro, the other Knight-Errant pounded a fist on his shoulder pauldron.

‘Gallor is on the grav-platform,’ Garro shouted over the roar of the wind and the screaming buzz of the swarm, pointing his sword down-range. ‘Regroup! I will be right behind you!’

But Varren slowed his pace. He wanted to watch.

Garro flicked a switch on the melta device and slung it back through the tear in the Walking City’s flank. The dull green cylinder vanished into the midst of the carrion fly horde and detonated. Pale yellow fire thundered through the framework and the decking, and later Varren would swear that he heard the insects scream.

The Walking City lurched, several of its supporting legs stumbling into the slopes of a steep mountain, and across on the far side of the great moving platform, sheets of ice and dislodged snowpack sloughed off the rock and collided with it.