‘Breacher rounds,’ she said, popping the slide open to show him the red Munitorum stencil on the yellow sleeve of the ready shell. ‘It will blow a hole in a bloody door. Knock a man down, even in armour.’

‘Do they… do they go off?’ he asked. ‘I mean, do they spoil. If you don’t use them?’

‘You’re an idiot,’ she snapped, staring at him with wide eyes. ‘What are you going on about?’

‘It doesn’t matter,’ he said, trying to sound calm even though a degree of panic was now rising in him, as if he were wading slowly and steadily deeper into an ice bath. ‘I shut the door. I locked it.’

‘Oh good,’ she said sarcastically. She sat down in the other armchair, then immediately got up again. ‘You saw it, right?’ she asked him. ‘You saw… that?’

‘I did,’ he said.

‘I’ve never…’ she murmured, pacing. ‘I swear by the Throne, I’ve never been so scared. That was… impossible. I mean, completely and utterly bloody impossible.’

‘In the most literal and scientific way,’ he agreed.

‘Is it still outside?’ she asked.

Drusher looked at the locked door and the chair wedged up against it.

‘Probably,’ he said. ‘I’d prefer not to check.’

Macks looked nervously around the small room. There were no other doors and no windows.

‘We can’t get out,’ she said. ‘If it’s outside the door…’

‘It can’t get in,’ he replied. ‘It will go away…’

She looked at him.

‘You didn’t freeze up,’ she said. ‘Why didn’t you freeze up? You always freeze up.’

Drusher shrugged.

‘I don’t know. Scientific curiosity,’ he said.

‘Groxshit,’ she said. ‘You kept it together somehow.’

‘I’ve rapidly developed a high threshold for strange,’ he said. After a moment, he added, ‘I think it’s beginning to hit me now, though.’

There was a soft noise. They both looked at the door sharply.

It was a scratching sound, like a hound pawing to be let in: the coarse, dry scrape of unfleshed distal phalanges clawing at the old wood of the door.

Macks cursed. They both backed away from the door.

‘It can’t get in,’ he said. ‘I locked it. It can’t get in.’

He felt that if he repeated it enough, it would become true.

Something started to happen to the door. It shivered slightly, then a dark patch began to appear at shoulder height, as though a blowtorch were being applied to the other side. The patch grew and spread. The wood began to flake and fall away. It looked for all the worlds of man as if the wood were simply and rapidly decomposing.

Macks swore again.

The decay spread, eating the wood away. Flecks of pulp billowed out from the collapsing surface, as though invisible swarms of boring insects were desiccating the wood and devouring it. Macks and Drusher could smell burned sawdust and mildew.