Alice had a sudden image of turning down a corridor and finding nothing but a blank wall ahead of her, then turning back to find the exit full of tiny, beady eyes. She pictured them coming at her, all in a rush, covering her in a carpet of vicious claws, needle-beaks pecking—

She tasted bile at the back of her throat, and gritted her teeth. There had to be a way out, somewhere.

At the next intersection, she stopped to listen. Ashes, halfway to the opposite tunnel, skidded to a halt and looked back at her.

‘Are you—’

‘Shh!’ After a moment, she closed her eyes. ‘Do you hear water?’

‘Yes,’ the cat said. ‘That way.’ He gestured with his head. ‘Which is all the more reason to go the other way—’

‘Come on.’

Alice ran towards the sound, and after an instant’s hesitation Ashes followed.

‘But,’ he said, ‘I can hear them coming this way!’

‘Just keep going!’

They turned a corner and found a small platoon of swarmers blocking their path. The little bird-things looked taken aback to find their prey rushing at them, and Alice took advantage of their hesitation to force her way through. Her foot came down heavily on one of them, bouncing it to one side as though she’d stepped on a tennis ball. She stumbled sideways, hit the brick wall hard enough to scrape her palms, but spun away from it and kept running. Another swarmer managed a wild stab as she went past, and she felt a bloom of pain at her ankle.

Then she was past them, and the skitter of claws behind her was almost drowned under the clearly audible rush of water. She turned another corner and saw – praise God – a door, a rusted iron bulkhead of the kind one might find on a steamship, half open and with the sound of water coming from beyond it. Alice slid sideways through the gap, and Ashes bounded through right behind her. Once he was through, she put her back to the door. For a horrible moment it resisted, and she thought her weight wouldn’t be enough. Then it swung a few inches, rusty hinges shrieking at the abuse, and stuttered through the rest of its arc until it hit the metal door-frame with a clang. Something in the mechanism clicked.

Alice leaned against the door, panting. She thought her lungs would collapse. After a moment her legs gave way, and she slid down the rough surface of the iron until she was sitting on the slimy brick floor.

‘Are you all right?’ said Ashes.

Alice was too busy gulping air to reply for a while. Taking stock, she found herself a mass of cuts, scrapes and bruises. Her cheek was smeared with blood, and she’d skinned her palms badly when she’d hit the wall.

When she could spare the breath to speak, she said, ‘I’m alive, I think. What about you?’