It took a minute, but Lemuel and Derkhan convinced Isaac that they had better flee the workshop now with the construct. They had better act on the information they had been given, even if they didn’t understand where it had come from.

Isaac protested weakly, tugging at the construct. He denounced David to Hell, then marvelled at the construct’s intelligence. He screamed rage and cast an analytical eye on the transformed cleaning engine. He was confused. Derkhan’s and Lemuel’s urgent insistence that they must move infected him.

“Yes, David is a godsdamn shit. And yes, the construct is a godsdamn miracle, Isaac,” hissed Derkhan, “but it’s going to be a wasted one if we don’t leave now.”

And in an infuriating, tantalizing end to the matter, the construct spread the dust out again as Isaac watched, and carefully scrawled: Later.

Lemuel thought quickly.

“There’s a place I know up in Gidd where we can go,” he decided. “It’ll do for tonight, and then we can make plans.” Derkhan and he moved quickly around the room, gathering useful items into bags they pilfered from David’s cupboards. It was clear they would not be able to return.

Isaac stood numb by the wall. His mouth was slightly open. His eyes were glazed. He shook his head incredulously.

Lemuel glanced up and saw him.

“Isaac,” he yelled. “Go and sort your shit out. We’ve less than an hour. We are leaving. Get off your arse.”

Isaac looked up, nodded peremptorily and stomped up the stairs, to stop and stand still again at the top. His expression was of bemused and miserable disbelief.

After some seconds, Yagharek came silently after him. He stood behind Isaac and peeled back his hood.

“Grimnebulin,” he whispered as softly as his avian throat allowed. “You are thinking of your friend David.”

Isaac turned sharply.

“No fucking friend of mine,” he countered.

“And yet he was. You are thinking of the betrayal.”

Isaac said nothing for several moments. Then he nodded. The look of horrified astonishment returned.

“I know betrayal, Grimnebulin,” whistled Yagharek. “I know it well. I am . . . sorry for you.”

Isaac turned away and walked brusquely to his laboratory space, began shoving bits and pieces of wire and ceramic and glass seemingly at random into a huge carpet bag. He strapped it, bulky and clanking, to his back.

“When were you betrayed, Yag?” he demanded.

“I was not. I betrayed.” Isaac stopped and turned to him. “I know what David has done. And I am sorry.”

Isaac stared in bewilderment, in denial and misery.

The militia attacked. It was only twenty minutes past seven.

The door flew open with a massive sound. Three militia officers came hurtling through into the room, their battering ram flying out of their hands.