They worked their slow way around their enclosure and found a hole in the stonework. There was no wall in New Crobuzon without its flaw. Through back tunnels, through metal-floored walkways and ladders, they entered Perdido Street Station. They had to leave their dead friends in the hidden garden. They could do nothing else.

In the enormous girdered cavern of Perdido Street Station, its vast central concourse, Judah and Cutter discarded their weapons and tried to clean their haint-fouled clothes, milled with late-night travellers and militia. They took a train.

They ricketed over the middling townscape of Ludmead with late-shift workers. When the cupolas of New Crobuzon University rose in the windows to the north, they got out at Sedim Junction Station. When at last the platforms were silent, Cutter led Judah onto the forking trainlines, toward the Kelltree and Dog Fenn branches. With the half-moon weak above the city’s lights, they crept onto the rails and set out south.

Some lines jutted into Collective territory-the Collective tried to run its own short services to match Triesti’s, from Syriac Rising to Saltpetre, Low Falling Mud to Rim. The conventional trains and those waving Collective flags would approach each other on the same lines, would halt above the many-angled roofs, a few yards apart, each on its side of barricades thrown across the lines themselves.

The Ribs curled hugely into the sky. Halfway up their length, scores of yards above the train lines, was the ragged jag where one of the Ribs had been broken by firing. The sharded edge of the break was a cleaner white, already yellowing. In the streets below Cutter saw the torn hole in the terrace where the broken end had fallen, crushing houses. It lay there still in the hole, among bomb damage, tons of bone ruin.

They walked an empty stretch of unclaimed railroad, chimneypots up from the street morass like periscopes peering curious, until they saw the piles of debris blocking the tracks. There were torches. Below in the alleyways was fighting, the incursion of the militia as the Collective’s barricadistes withdrew and fell back a few streets, firing from street kiosks, voxiterator booths, from behind iron pillars.

A war train was approaching from beyond the barricade-they could see its lights and the gush of it. It fired as it came, sending shells into the militia in the streets. It came up from the south, from Kelltree’s docks.

"Halt, you fuckers!" came from the barrier. Cutter was ready to beg entrance, but Judah spoke in a huge voice, coming out of stupor.

"Do you know who you’re talking to, chaver? Let me through, now. I’m Judah Low. I’m Judah Low. "