But they passed over Cockscomb Bridge, where they felt isolated and open, where the sun seemed to etch out their edges and mark them for attack, and slipped into Petty Coil. The city seemed to close its lips around them and they felt safer again.

There were other beggars here, walking in the train of local notables, earringed villains and fat money-lenders and pinch-lipped madams. Andrej stirred slightly and Yagharek closed his mind down again, laid hands on him efficiently.

Here there were backstreets. Isaac and Yagharek could peel away from the main roads and head down along overshadowed alleys. They passed under washing that linked the facing terraces of tall, narrow streets. They were watched by men and women in underclothes who idly leaned over balconies, flirting with their neighbours. They passed piles of rubbish and broken sewer coverings, and children leaned out from above and spat at them without rancour, or threw little pebbles and ran away.

As always, they sought the railway line. They found it at Sly Station, where the Salacus Fields trains branched away from the Sud Line. They sidled up to the raised path of arches that wove unsteadily above the cobbles of Spit Hearth. The air above the raucous crowds was reddening as the sun wound slowly towards gloaming. The arches were fouled with oil and soot, sprouting a microforest of mould and moss and tenacious climbing plants. They swarmed with lizards and insects, aspises sheltering from the heat.

Isaac and Yagharek ducked into a dirty cul-de-sac by the track’s concrete and brick foundations. They rested. Life rustled in the urban thicket above them.

Andrej was light, but he was beginning to weigh them down, his mass seeming to increase with every second. They stretched their aching arms and shoulders, drew deep breaths. A few feet away, the crowds emerging from the station thronged past the entrance to their little hideaway.

When they had rested and rearranged their burdens, they braced themselves and set out again, into the backstreets once more, walking in the shadow of the Sud Line, towards the city’s heart, the towers not yet visible over the surrounding miles of houses: the Spike and the turrets of Perdido Street Station.

Isaac began to talk. He told Yagharek what he thought would happen that night.

Derkhan made her way through the reclaimed filth of the Griss Twist dump towards the Construct Council.

Isaac had warned the great Constructed Intelligence that she would be coming. She knew she was expected. The idea made her uncomfortable.

As she approached the hollow that was the Council’s lair, she thought she heard a susurration of lowered voices. She stiffened instantly, and drew her pistol. She checked that it was loaded, and that the firing pan was full.