‘Voriet needs to rest,’ said Drusher.

‘No time,’ replied Nayl.

‘He needs to rest,’ Drusher insisted.

‘I know he does, magos,’ said Nayl. ‘But there is no time for that.’

Macks leaned over the rail and looked down.

‘That fire’s bad,’ she said. The air around them was already hazed with smoke. It was dirty and black, and making them cough. Far below, the sump was a blazing sea of flames, a furious petrochemical fire that was beginning to choke the tower with murky, toxic smog.

‘On the plus side,’ she said, ‘I guess it will take out the Loom.’

‘There’s that,’ said Nayl. ‘But we have to find an exit. Another ten minutes, and it won’t be possible to breathe in here. Besides, that fire’s going to climb.’

‘I can go on,’ said Voriet. Drusher could tell he was lying. Every time Voriet coughed because of the rising smoke, it aggravated the pain of his broken bones. He looked dead on his feet.

Nayl put his arm around Voriet to support him and began to climb the next staircase. Macks and Drusher looked at each other then followed. They could feel the intense heat from below. They followed the stairs up to another inspection catwalk, traced that to its end and took the next set of metal steps up. The Loom’s whirring mechanisms were wafting strange circles and hoops in the slow smoke, like ripples in water.

‘Do you think he’s dead?’ Macks asked Drusher.

‘Eisenhorn?’

‘Yeah.’

‘You heard that scream,’ said Drusher.

‘I felt it,’ she replied. ‘I don’t want to think what they might have done to him to make him scream like that.’

Nayl paused to look up. The eerie light was still glowing above them, but the smoke in the air had made it foggy.

‘Just a few more levels,’ Nayl said. ‘At the main gantry, there was an exit into the rest of the fortress. That’s how me and the magos got in. I think that’s the only way out. Can you do that, Darra?’

Voriet nodded. His face was pinched and pale, and beaded with dirty perspiration. His clothes were sticking to him.

‘Let’s go then,’ said Nayl.

Voriet reached out with his good hand and caught Nayl’s arm. Nayl stopped.

‘Back up,’ he hissed to the others.

There was an animation on the platform ahead of them, a skeleton that had been bleached white. Odd symbols had been scratched into its bones. It limped towards them, fixing them with the tiny green pinpricks of light that served as its eyes.

They moved back along the platform, hustling Voriet along, and found a short flight of steps down onto an access catwalk. It felt wholly wrong to be going down rather than up.

‘More steps ahead,’ said Nayl. ‘A different way up.’