Isaac sighed beatifically. He looked around and ran over to the few boxes of cocoons and eggs and grubs. He shoved them over to the window, leaving only the big, dying, multicoloured caterpillar undisturbed.

Isaac grabbed handfuls of eggs and hurled them out of the window after the fleeing shapes. He followed them with caterpillars that twisted and jack-knifed as they fell towards the paved ground. He shook cages that rattled with delicate pupating shapes, and emptied them out of the window. He poured out a tank of water-born larvae. For these young, it was a cruel liberation, a few seconds of freedom and rushing air.

Eventually, when the last tiny shape had disappeared below, Isaac closed the window. He turned back and surveyed the warehouse. He heard a faint drone of wings, and saw a few airborne shapes circulating the lamps. An aspis, a handful of moths or butterflies, and a couple of small birds. Well, he thought, they’ll find their own way out, or they wont last long and I can clear them out when they starve.

Littering the floor in front of the window were some of the runts and the dying, the weaklings, that had fallen before they could fly. Some were dead. Most crawled feebly this way and that. Isaac set to cleaning them out.

“You have the advantage that you are (a) rather beautiful; and (b) rather interesting, old chum,” he said to the huge, sickly grub as he worked. “No, no, don’t thank me. Just consider me a philanthrope. And also, I don’t understand why you don’t eat. You’re my project,” he said, jettisoning a dustpan full of feebly crawling bodies into the night air. “I doubt you’ll last the night, but fuck it, you’ve appealed to my pity and my curiosity and I’ll have one last stab at rescuing you.”

There was a shuddering bang. The door to the warehouse had been hurled open.

“Grimnebulin!”

It was Yagharek. The garuda stood in the dimly lit space, legs apart and arms clutching at his cloak. The jutting shape of his wooden wing disguise swayed unrealistically from side to side. It was not properly attached. Isaac leaned over the rail and frowned.

“Yagharek?”

“Have you forsaken me, Grimnebulin?”

Yagharek was shrieking like a tortured bird. His words were almost impossible to understand. Isaac gesticulated at him to calm down.

“Yagharek, what the fuck are you talking about…?”

“The birds, Grimnebulin, I saw the birds! You told me, you showed me, they were for your research…what has happened, Grimnebulin? Are you giving up?”

“Hang on…how in the name of Jabber’s arse did you see them fly away? Where’ve you been?”

“On your roof, Grimnebulin.” Yagharek was quietening. He was calmer. He radiated a massive sadness. “On your roof, where I perch, night after night, waiting for you to help me. I saw you release all the little subjects. Why have you given up, Grimnebulin?”

Isaac beckoned him up the stairs.

“Yag, old son…Damn, I don’t know where to start.” Isaac stared up at the ceiling. “What the arse were you doing on my roof? How long have you hung about up there? ‘Stail, you could’ve kipped down here, or something…that is absurd. Not to say a bit eerie, thinking of you up there while I work or eat or shit or whatnot. And-” he held up his hand to cut off Yagharek’s response “-and I have not given up on your project.”

He was silent for a while. He let the words sink in. He waited for Yagharek to calm, to return from the miserable little hollow he had carved for himself.

“I haven’t given up,” he repeated. “What’s happened is quite good, actually…We’ve entered a new phase, I think. Out with the old. That line of research has been…ah…terminated.”

Yagharek bowed his head. His shoulders shuddered slightly as he breathed out lengthily.

“I do not understand.”

“Right, well, look, come over here. I’m going to show you something.”

Isaac led Yagharek over to the desk. He paused momentarily to tut at the huge caterpillar that sagged on its side in the box. It stirred weakly.

Yagharek did not spare it a glance.

Isaac pointed to the various bundles of paper that propped up overdue library books and teetered on his desk. Drawings, equations, notes and treatises. Yagharek began to sift slowly through them. Isaac guided him.

“Look…See all the damn sketches everywhere. Wings, for the most part. Now, the starting point for the research was the wing. Seems sensible, don’t it? So what I’ve been about is understanding that particular limb.

“The garuda who live in New Crobuzon are useless for us, by the way. I put up notices in the university, but apparently there’re no garuda students this year. I even tried to argue for the sake of science with a garuda…uh…community leader…and it was a bit of a disaster. Let’s put it that way.” Isaac paused, remembering, then blinked himself back to the discussion. “So instead, let’s look to the birds.

“Now, that leads us to a whole new problem. The little beggars, the humming birds and wrens and whatnot are all interesting and useful in terms of…y’know…broad background, the physics of flight and what have you, but basically we’re looking at the big boys. Kestrels, hawks, eagles if I’d got hold of any. Because at this stage I’m still thinking analogously. But I don’t want you to think I’m close-minded…I’m not studying the mayfly or whatever just out of interest, I’m trying to work out if I can apply it.

“I mean, I’m presuming you’re not fussy, right, Yag? I’m presuming that if I graft onto your back a pair of bat or bluebottle wings, or even a wind-polyp’s flightgland, you’re not going to be fussy. Might not be pretty, but it’s just about getting you into the air, right?”

Yagharek nodded. He was listening fiercely, sifting through the papers on the desk as he did so. He was intent on understanding.

“Right. So it seems reasonable, even given all that, that it’s the big birds we should be looking at. But of course…” Isaac rummaged among the papers, grabbed some pictures from the wall, handed sheafs of the relevant diagrams to Yagharek. “Of course, that turns out not to be so. I mean, you can get so far on the aerodynamics of birds, all useful stuff, but it’s actually very misleading to be looking at them. Because the aerodynamics of your body are so fucking different, basically. You ain’t just an eagle with a scrawny human body attached. I’m sure you never thought you were…I don’t know how your maths and physics are, but on this sheet here-” Isaac found it and passed it over “-are some diagrams and equations which show you why big birds’ flight ain’t the direction to be looking. Lines of force all wrong. Not strong enough. That sort of thing.

“So, I turn to the other wings in the collection. What if we tacked on dragonfly wings or what have you? Well, first of all there’s the problem of getting hold of insect wings big enough. The only insects big enough already aren’t going to just hand ‘em over. And I don’t know about you but I don’t fancy fucking off into the mountains or wherever to ambush an assassin beetle. Get our arses kicked.

“What about building them to our specifications? Then we can get the size right and the shape. We can compensate for your…awkward form.” Isaac grinned and continued. “Trouble is, material science being what it is, we might be able to make them exact enough, and light enough, and strong enough, but I honestly doubt it. I’m working on designs that might work, but might not. I don’t think the odds are good enough.

“Also, you’ve got to remember that this whole project is dependent on you getting Remade by a virtuoso. I’m glad to say I don’t know any Remakers, which is the first thing, and the second is they’re usually more interested in humiliation, industrial power or aesthetics than in something as intricate as flight. There are shit-loads of nerve endings, loads of muscles, ripped-up bones and the like floating around in your back, and they’d have to get every one exactly right if you were going to have the slightest chance of getting airborne.”