As he drew closer, Isaac could feel it too. Snatches of alien sensation slithered like lightning-quick eels through his cerebellum. He blinked and coughed slightly, in thrall suddenly and briefly to the sensation of emotions that were not his clogging up his throat. Isaac shook his head and squeezed his eyes hard shut.

“Gazid,” he snapped. “Walk slowly round it.”

Lucky Gazid did as he was told. The caterpillar toppled over in its eager attempts to right itself, to follow him, to track him down.

“Why does the thing want me?” moaned Lucky Gazid.

“Well I don’t know, Lucky,” said Isaac tartly. “The poor thing’s hurting. Looks like it wants whatever you’ve got, Lucky old son. Empty your pockets slowly. Don’t worry, I’m not going to nick anything.”

Gazid began to pull strips of paper and handkerchiefs from the folds of his soiled jacket and trousers. He hesitated, then reached inside and pulled two fat packets from his inner pockets.

The grub went berserk. The disorienting shards of synaesthetic feeling whirled through Isaac’s and Gazid’s heads again.

“What the fuck’ve you got?” said Isaac through clenched teeth.

“This one’s shazbah,” said Gazid hesitantly and waved the first packet at the cage. The grub did not react. “This one’s dreamshit.” Gazid held the second envelope over the caterpillar’s head, and it all but balanced on its rear end to reach it. Its piteous wails were not quite audible, but they were acutely sensible.

“There we go!” said Isaac. “That’s it! The thing wants dreamshit!” Isaac held out his hand to Gazid and clicked his fingers. “Give it to me.”

Gazid hesitated, then handed over the packet.

“Lot of stuff there, man . . . that’s a lot of moolah there, man . . .” he whimpered. “You can’t just take it, man . . .”

Isaac hefted the pouch. It weighed about two or three pounds, he estimated. He pulled it open. Again the emotional wails burst piercingly up from the caterpillar. Isaac winced at the poignant and inhuman begging.

The dreamshit was a mass of brown, sticky pellets that smelt like very burnt sugar.

“What is this stuff?” Isaac asked Gazid. “I’ve heard of it, but I know arse-all about it.”

“New thing, ’Zaac. Expensive stuff. Been around a year or so. It’s . . . heady stuff . . .”

“What does it do?”

“Couldn’t describe it really. Want to buy some?”

“No!” said Isaac sharply, then hesitated. “Well . . . Not for me, anyway . . . How much would this packet cost, Lucky?”

Gazid hesitated, doubtless wondering how much he could exaggerate.

“Uh . . . about thirty guineas . . .”

“Oh fuck off, Lucky . . . You’re such a piss-artist, old son . . . I’ll buy this off you for . . .” Isaac hesitated. “For ten.”

“Done,” said Gazid instantly.