‘What did you see?’ asked Macks.

‘Doesn’t matter,’ said Drusher. He picked up the insect by its wing cases and held it up. Its legs writhed. ‘How is this here? See the red banding on the thorax? That’s swarm-phase colouring. These things live in huge colonies. When overcrowding becomes an issue, it stimulates the release of serotonin, and the insects shift from statary to migratory morphs. They change colour, and then they begin an upsurge.’

‘So?’ asked Macks again.

‘Well, you wouldn’t see just one coloured like this,’ said Drusher. ‘By definition, an upsurge morph is never seen alone.’

Macks stared at him levelly.

‘I’m very glad you find the insect fascinating,’ she said. ‘Can we get on now?’

‘Yes, of course,’ he said. He shook the insect off his hand, and it fluttered away. They started up the next flight of stairs, Nayl leading, then Macks, then Drusher helping Voriet.

‘There’s another one,’ said Voriet. Another locustform had settled on the steps.

‘Why don’t we turn this into a nature ramble?’ Macks hissed back at them.

‘There’s quite a few of them, actually,’ said Drusher. Two more insects fluttered past. Several more were crawling on the steps and the rail.

‘Where are they coming from?’ asked Macks.

‘Uhm, my original point,’ said Drusher.

More insects began to billow around them.

‘Ugh,’ said Macks, brushing one away, ‘they are swarming.’

Drusher peered over the rail. By the light of the sump fire far below, he could see thousands of tiny motes swirling in the spaces between the gears of the Loom. Hundreds of thousands.

‘Yes, they are,’ he said. ‘A major upsurge outbreak.’

‘Could it be the heat?’ asked Nayl. ‘The heat of the fire?’

‘Oh, Throne!’ exclaimed Macks. ‘Yes, let’s all stop and study nature!’

An insect landed on Nayl’s cheek. He flicked it away.

‘She’s right,’ he said. ‘Keep moving.’

They made their way up three more platform sections. From a curved catwalk, they could clearly see the main gantry above them, bathed in noxious light. The air was full of churning insect clouds. The locustforms were settling everywhere: on the catwalk deck, on the rail, on their clothes. The chirring drone of their stridulation was as loud as the din of the furious Loom.

‘They’re making my damn skin crawl,’ yelped Macks, flicking one off her earlobe.

‘Focus,’ snapped Nayl, brushing more insects off his scalp. ‘Look…’

He pointed.

‘This walkway curves all the way around to that staircase on the far side of the tower. See? If we can get around there, we can go up. The main hatch is up there.’

‘What about Eisenhorn?’ asked Drusher. He spat instinctively as an insect nearly flew into his mouth.

‘You three go around,’ said Nayl. ‘I’m going to sneak up this way and see if I can get a look at the gantry.’