The pilot was Remade, his arm a python that he strapped to him. He hardly spoke. Over three days, all Cutter learnt was that he had once worked for a crime-boss, that he was pledged to the Collective.

"We have to go fast," Cutter said. "Something’s coming out of the cacotopic zone." He knew it must sound like some Torque-beast was hunting, and he did not correct the impression. "We have to find the Council."

He checked the mirrors he carried. The glassworks had built a beautiful replacement. He had shown them to Madeleina di Farja, explaining what they were for.

"How many times have you done it?" she said, and he laughed.

"None times. But Judah Low told me how."

Cutter stared down into the acres of air specked with birds and windblown scobs. They flew over raincloud like a smoke floor. At the limits of their vision, miles south, they saw people. A long spread-out column through the landscape, the vanguard of the rogue train, who went ahead even of the graders and the bridge-builders.

"Fly past, not too close," Cutter said. "Let them know we don’t mean no harm." His heart went fast. It took them an hour to trace the scattered miles of Council back, to the graders sweeping aside debris, patting down and hammering down the ground, and then to the track-layers moving with precision that made them seem automata, and then to the perpetual train.

"There."

Cutter watched it. Its flatbeds, its carriages and its built-up towers, its bridges swaying, the mottled colours of its addenda, the skull and head adornments, smoke from all of its chimneys, those of the engines and those that specked its length. And all around it the hundreds of Councillors moving along it and on it, in the gap through which it travelled. A bolt of hexed gunpowder combusted below them.

"Dammit, they think we’re attacking. Swing round, give them a berth, let’s lower some flags."

The train edged forward along the unrolling tracks, the line behind it dismantled as it went. In its wake was debris, a cut of altered ground.

"Gods they’re moving fast. They’ll be at the city within weeks," Cutter said. Weeks. Too slow. Too late. Besides, he thought, what can it do? What can it do?