The cat was already gone, slipping lithely between two of the bookcases. Alice stared after him, seeing nothing but darkness beyond, and felt utterly foolish.

Perhaps he’s abandoned me here, she thought. For a joke? Or is he really trying to make sure I never come back? She was starting to question the wisdom of following a talking cat in the first place. Cats were notoriously fickle creatures.

Ashes re-emerged into the candlelight. ‘He’s not here yet,’ he said. ‘Come in, but move carefully, and don’t touch anything.’

She looked dubiously at the gap between the shelves.

‘You’ll fit,’ Ashes said. ‘Although you’d fit better if you were a cat.’ He turned and slipped easily through the narrow crack.

Alice edged sideways into the angle formed by the two bookshelves, pushed her arm through the space between them, and tried to force her shoulders through. To her surprise, it wasn’t difficult. She got the distinct sense that the shelves were moving apart, or actually bending back as though they were made of clay. Something passed across her skin, a faint tingle like a wall of warm mist, and her next breath brought a lungful of air so unlike the dry, dusty smell of the library that she stopped short, wedged halfway between the bookshelves.

‘Don’t just stand there,’ came Ashes’ voice. ‘You’ll let the damp out.’

Alice dragged herself through with a final effort, carefully bringing the candle in last of all. When she turned round, she discovered she didn’t need it, and nearly dropped it in surprise.

Inside, the little cluster looked nothing like the library beyond. The backs of the shelves were enormous, shadowy things, more like stone than wood. The space they enclosed was much larger than it had appeared from the outside, as big as a good-sized garden. The floor had changed from dusty stone to a rich, soft loam, damp and clingy on her feet. The air smelled wet, warm, and thick with the scent of rotting, growing things.

In the centre of the place was a circular pond. It was the only way Alice could think to describe it, in spite of the ridiculousness of having a pond inside a library. In the middle of the pond was an island, only a few feet across, and on the island a small fire of sticks and dry leaves crackled merrily. Balanced on an iron stand above the fire was a small iron cauldron, of the sort a witch in a story might use to boil unwary children. Something was bubbling in it, and the rising steam mixed with the smoke of the fire as it rose towards the invisible ceiling.