The wheel spun; the light changed; the sound changed.

The glow from outside went from the dim of streetlights, down to darkness, then slowly back up to something luminous but odd. The last of the car engines sounded very far away, and then was gone. At last the wheel slowed and stopped.

Deeba stood, frozen, her hands to her mouth, in the strange not-dark. Zanna blinked several times, as if waking. The two looked at each other, and around at the room, all different in the bizarre light, full of impossible shadows.

“Quick! Undo it!” Deeba said at last. She grabbed the wheel and tried to turn it backwards. It was wedged stubbornly, as if it hadn’t moved for years. “Help!” she said, and Zanna added her strength to Deeba’s, and with a burst of effort they made the metal move.

But the wheel just spun free. It wasn’t catching on anything. It whirred heavily around, but the light didn’t change, and the noise of traffic didn’t return.

London didn’t come back on.

“Zanna,” said Deeba. “What did you do ?”

“I don’t know,” whispered Zanna. “I don’t know.”

“Let’s get out of here,” Deeba said. Zanna grabbed her arm and they ran back into the corridor.

The peculiar light was shining around the edges of the doorway they had come in by, as if a giant black-and-white television were playing just outside. Deeba and Zanna went for it full-tilt, and shoved it open.

They stumbled out. And stopped. And looked around. And let their mouths hang open.

It was not night anymore, and they were not in the estate. They were somewhere very else.

Just as it had when they entered, the door opened on waste ground between tall buildings, and to either side were big metal bins and spilt rubbish. But the tower blocks were not those they had left behind.

The walls just kept going up. Everywhere they looked, they were surrounded by enormous concrete monoliths that dwarfed those they remembered, and stood in more chaotic configurations. Not a single one of them was broken by a single window.

The door swung shut, and clicked. Zanna tugged it: of course it was locked. The building they’d emerged from soared into a sky glowing a peculiar glow.

“Maybe that room’s, like…a train carriage…” Deeba whispered. “And we’ve come down the line…and…and it was later than we thought…”

“Maybe,” whispered Zanna doubtfully, trying the door again. “So how do we get back?”

“Why did you turn it?” Deeba said.

“I don’t know, ” said Zanna, stricken. “I just…thought like I had to.”

Holding each other’s arms for comfort, peering everywhere wide-eyed, Zanna and Deeba crept into the passageways between the walls.

“I’m calling Mum,” Deeba said, and took out her phone. She was about to dial when she stopped, and stared at the screen. She showed it to Zanna. It was covered in symbols they’d never seen before. Where the reception bar usually was was a sort of corkscrew. Instead of the network sign was a weird pictogram.

Deeba scrolled through her address book.

“What’s that mean?” said Zanna.

“Those aren’t my friends’ names,” whispered Deeba. Her phone’s contact list contained random words in alphabetical order. Accidie, Bateleur, Cepheid, Dillybag…

“Mine’s the same,” said Zanna, checking her own. “Enantios? Floccus? Goosegog? What is that ?”

Deeba dialed her home number.

“Hello?” she whispered. “Hello?”

From the phone sounded a close-up buzzing like a wasp. It was so loud and sudden in that silent place that Deeba turned it off in alarm. She and Zanna stared at each other.

“Let me try,” said Zanna. But dialing her number led to the same unpleasant insect noise. “No reception,” she said, as if that were all that was wrong. Neither of them said anything more about the strange words or pictures on their phones.

They went deeper into the cavern between the windowless buildings.

“We have to get out of here,” said Zanna, speeding up.

They ran past windblown old newspaper, deserted tin cans, and the rustling of black rubbish bags. In growing terror they turned left then right then left, and then Zanna came to a sudden stop, and Deeba bumped into her.

“What?” said Deeba, and Zanna hushed her.

“I thought…” she said. “Listen.”

Deeba bit her lip. Zanna swallowed several times.

For long seconds there was silence. Then a very faint noise.

There was a rustling, what might be a light footfall.

“Someone’s coming,” whispered Zanna. Her voice was halfway between hope and despair— would this person help, or be more troubles?

Then she slumped, and pointed.

It was just a torn black rubbish bag, billowing nearby. It scraped gently against the ground.

Deeba sighed and watched it despondently as it fluttered a little closer. There was more rubbish behind it: with a clatter a can rolled into view, and there was the whisper of newspaper. A little collection of discarded stuff swirled at the passage entrance. The girls leaned against the wall.

“We got to think,” Deeba said, and tried and failed to use her phone again.

“Deeba,” Zanna whispered.

There was more rubbish than had been there a moment before. The black plastic, and the can, and the newspapers, had been joined by greasy hamburger wrappers, a grocery bag, several apple cores, and scrunched-up clear plastic. The rubbish rustled.

More rolled into view: chicken bones, empty tubes of toothpaste, a milk carton. Debris blocked off the way they had come.

Deeba and Zanna stared. The rubbish was moving towards them. It was coming against the wind.

As the girls began to creep backwards, it seemed as if the rubbish realized they were onto it. It sped up.

The cartons and cans rolled in their direction. The paper fluttered for them as madly as agitated butterflies. The plastic bags reached out their handles and scrambled towards the girls.

Deeba and Zanna screamed and ran. They heard the manic wet rustle of the predatory rubbish.

They raced through the maze of walls, desperate to get away.

Behind them there was a scrunching of paper, a percussion of cardboard, the squelch of damp things moving fast. The girls were fighting for breath.

“I…can’t…” said Deeba. Zanna tried to pull her along, but Deeba could only flatten against a wall. “Oh help,” she whispered. Zanna stood in front of her, between her friend and their pursuers.

The rubbish was close. It had slowed, and was creeping towards them. The stinking heap came with motions as careful and catlike as its odd shapes would allow. The stench of old dustbins was strong.

Ragged black plastic reached out with its rip-arms, trailing rubbish juice like a slug’s slime. Zanna raised her arms in despairing defense, and Deeba held her breath and closed her eyes.