“Listen, Lucky, you little puke. How can you be hurting, you’re so strung out now you can hardly stand. How dare you crash round my house, you fucking junkie . . .”

“Oy!” Gazid shouted suddenly. He sneered up at Isaac, breaking his flow. “Lin isn’t here now, but I’m hungry for something, and I want you to help me or I don’t know what I might end up saying, if Lin won’t help me, you can, you’re her knight in shining armour, her love-bug, she’s your ladybird . . .”

Isaac drew back a fat meaty fist and smashed Lucky Gazid in the face, sending the little man yards through the air.

Gazid squealed in astonishment and terror. He scraped his heels on the bare wood and scrabbled towards the stairs. A star of blood radiated out from below his nose. Isaac shook blood from his knuckles and stalked towards Gazid. He was cold with rage.

Think I’m going to let you talk like that? Think you can blackmail me, you little shit? he thought.

“Lucky, you should leave right fucking now if you don’t want me to take your head off.”

Gazid crawled to his feet and burst out crying.

“You’re fucking crazy, Isaac, I thought we were friends . . .”

Snot and tears and blood dripped onto Isaac’s floor.

“Yeah, well, you thought wrong, didn’t you, old son? You’re nothing but a fucking dreg, and I . . .” Isaac broke off from his contumely and stared in astonishment.

Gazid was leaning against the empty cages on which the caterpillar’s box lay. Isaac could see the fat grub wriggling, jack-knifing in excitement, twisting desperately against the wire front, squirming with sudden reserves of energy towards Lucky Gazid.

Lucky hovered, terrified, waiting for Isaac to finish.

“What?” he wailed. “What are you going to do?”

“Shut up,” hissed Isaac.

The caterpillar was thinner than it had been on its arrival, and its extraordinary peacock-feather colours were dulled, but it was undoubtedly alive. It rippled its way around its little cage, feeling through the air like a blind person’s finger, faltering towards Gazid.

“Don’t move,” hissed Isaac, and edged closer. The terrified Gazid obeyed. He followed Isaac’s line of sight and his eyes widened at the sight of the huge grub rooting its way around the little cage, trying to find a way towards him. He snatched his hand from the box with a little cry and started backwards. Instantly, the caterpillar changed direction, trying to follow him.

“This is fascinating . . .” said Isaac. As he watched, Gazid reached up and clutched his head, shaking it suddenly and violently as if it was full of insects.

“Oh, what is happening in my head?” Gazid stuttered.