He tweaked the copper, hardened it.

Tansell removed his hands and looked up at Isaac. The helmet on his head was unwieldy, and its provenance from a colander was still absurdly obvious, but it was perfect for their needs. It had taken him a little more than fifteen minutes to fashion.

“I’m going to put a couple of holes in, thread a piece of leather through for a chinstrap, just in case,” he muttered.

Isaac nodded, impressed.

“That’s perfect. We need…uh…seven of those, one of them for a garuda. That’s a rounder head, remember. I’m going to leave you to it for a minute.” He looked over at Derkhan and Lemuel. “I think I’d better liaise with the Council,” he said.

He turned and traced his way through the dump labyrinth.

“Good evening, der Grimnebulin,” said the avatar, in the heart of the rubbish. Isaac nodded a greeting to it, and to the enormous skeleton shape of the Council itself, which waited beyond. “You did not come alone.” His voice was emotionless as ever.

“Please don’t start,” said Isaac. “We are not going to get into this on our own. We are one fat scientist, a crook and a journalist. We need some fucking professional back-up. These are people who kill exotic animals for a damn living, and they have not the slightest damn interest in telling anyone about you. All they know is that some fucking constructs are going to be there with us. Even if they could work out who or what you were, they’ve probably broken at least two-thirds of New Crobuzon’s laws by now, so they ain’t about to damn well go running to Rudgutter.” There was silence. “Just damn well compute it, if you want. You are in no risk at all from the three reprobates busy making helmets.”

Isaac imagined that he felt a trembling under his feet, as the information raced through the Council’s innards. After a long pause, the avatar and the Council nodded warily. Isaac did not relax.

“I’ve come for those of yourself you can risk for tomorrow’s business,” he said. The Council nodded again.

“Very well,” said the Construct Council slowly with the dead man’s tongue. “First, as we discussed, I will take the part of caretaker. Have you the crisis engine?”

Something hard moved across Isaac’s face. It went quickly.

“Right here,” he said, and put one of his bags down in front of the avatar. The naked man opened it and bent down to peer inside at the tubes and glass within, giving Isaac a sudden, vile view into the scabbing hollow of his skull. He picked it up and walked over to the Council with it, depositing it before the enormous figure’s crotch.

“So,” said Isaac. “You hang on to that, just in case they find our shack. Good idea. I’ll be back for it in the morning.” He glowered. “Which of you are coming with us? We need some power behind us.”

“I cannot risk discovery, Grimnebulin,” the avatar said. “If I were to come in my hidden selves, those construct bodies that work by day in grand houses and building sites and bank vaults, biding their time and accumulating knowledge, and they were to come back battered and broken, or not come back at all, I would leave myself open to the inquiry of the city. And I am not ready for that. Not yet.” Isaac nodded slowly. “Accordingly, I will be coming with you in those shapes that I can afford to lose. That will arouse confusion and bewilderment, but not suspicion of the truth.”

Behind Isaac, the rubbish began to skitter and fall away. He turned.

From the reams of discarded objects, particular aggregations of trash were separating themselves. Like the Construct Council itself, they were clotted together from the materia of the dump.

The constructs mimicked the form and size of chimpanzees. They clattered and clanged as they moved, with a weird and unsettling sound. Each was unique. Their heads were kettles and lampshades, their hands were vicious-looking claws ripped from scientific instruments and scaffolding joints. They were armoured in great scabs of metal plating torn, roughly welded and riveted to their bodies, which scampered across the wasteland in an unsettling half-simian motion. They were created with an extraordinary sense of found aesthetics.

If they lay still, they would be invisible: nothing but a random accretion of old metal.

Isaac gazed at the chimp-things, swinging and jumping, dripping water and oil, ticking with clockwork.

“I have downloaded into each of their analytical engines,” said the avatar, “as much memory and capacity as they will hold. These of me can obey you, and understand the urgency of doing so. I have given them viral intelligence. They have been programmed with the data to recognize the slake-moths, and to attack them. Each is built with acid or phlogistic agent within its midriff.” Isaac nodded, wondering at the casual ease with which the Council created these murderous machines. “You have worked out the best plan?”

“Well…” said Isaac. “We’re going to prepare tonight. Work out some kind of…uh…gear up, you know, plan with our…additional staff. Then tomorrow at sixish we’ll meet Yag here, assuming the stupid bastard hasn’t got himself killed. And then we’re going to get into the Riverskin ghetto, using Lemuel’s expertise.

“Then we go moth-hunting.” Isaac’s voice was hard and staccato. He spat out what he needed to say quickly. “The thing is we’ve got to separate them. We can take one, I think. Otherwise, if there are two or more, then one will always be in front of us, able to flash the wings. So we’re going to scope the place out, see if we can work out where they are. It’s hard to say without seeing it. We’ll take the amplifier and channeller you used on me, as well. It might help us get one interested, get it sniffing. Push a little peak through the background mental noise, or something. Can you attach other helmets to the one engine? D’you have any extras?” The avatar nodded. “You’d better give them to me, and show me the different functions. I’ll get Tansell to adjust them, add some mirrors.

“Thing is,” said Isaac thoughtfully, “it can’t just be the strength of the signal that attracts them, or it would only ever be the seers and communicatrixes and so on that got taken. I think they like particular flavours. That’s why the runt came for me. Not because there was a big waving trail above the city, any old trail, but because it recognized and wanted that particular mind. And…well, now, maybe the others are going to recognize it as well. Maybe I was wrong that only the one would ever recognize my mind. They must’ve sniffed it last night.” He looked at the avatar thoughtfully. “They’re going to remember it as the trail their brother or sister was after when it got killed. I don’t know if that’s a good thing or a bad thing…”

“Der Grimnebulin,” said the dead man after a moment, “you must bring at least one of my little selves back with you. They must download what they have seen into me, the Council. I can learn so much of the Glasshouse from this. It can only help us. Whatever happens, one must get free.”

There were several moments of silence. The Council waited. Isaac thought for something to say, and then could not. He looked up into the avatar’s eyes.

“I’ll be back tomorrow. Have your monkey-selves ready then. And then I will…I will…see you again,” he said.

The city basked in extraordinary night-heat. The summer reached a critical moment. In the striae of dirty air above the city’s core, the slake-moths danced.

They flitted giddily over the minarets and crags of Perdido Street Station. They twitched their wings infinitesimally, edging expertly up the thermals. Skeins of inconstant emotion spun out from their cavorting.