‘Isaac.’ This produced no response, so she strode over and grabbed him by the collar, jerking him to his feet. ‘Isaac! What the . . . What was that?’

‘The prisoner. This is a prison-book, after all.’ He glanced up at her, then closed his eyes again. ‘The Dragon.’

Alice let him go, and he slumped forward.

‘A dragon?’ she said. ‘Really a dragon?’

‘The Dragon,’ Isaac said.

‘There’s only one?’

‘Nobody knows where it came from. Some Reader caught it in a book a long time ago, and nobody has ever been able to find another one. And even the book has been lost for centuries.’

Alice felt a hint of fear, clutching like a cold hand at her chest, but she pushed it ruthlessly away.

‘If it was lost, how come you came looking for it?’

‘My master found a hint that it had been hidden somewhere in Geryon’s library, and he talked Ending into sneaking me in to try and find it.’ He looked accusingly at Alice. ‘And you got us stuck inside it!’

Alice scanned the horizon. There was no sign of a dragon.

‘If this is a prison-book,’ she said, ‘that means we’ve got to find the prisoner, and force it to submit. How much do you know about the Dragon?’

‘Nothing!’ Isaac said. ‘I wasn’t supposed to go inside. My master didn’t tell me anything about it!’

‘We’ve got to do something.’

‘We’re going to get eaten, that’s what we’re going to do,’ Isaac said. ‘We—’

‘You sound like Ashes,’ Alice said. ‘He was certain we were going to die too. But we didn’t. So would you quit—’

The rocks shifted underneath her, this time more violently. The one they were standing on, a huge, flat-topped boulder, jumped as though something had struck it hard from beneath, then sagged on one side until it was canted like the deck of a sinking ship. The movement shocked Isaac out of his hypnotized immobility, and he scrambled for the high end of the rock, looked down, and leaped over the side.

‘Isaac! Wait!’ Alice hurried to the edge and found him scrambling up the face of the next boulder. ‘Where are you going?’

He didn’t have the chance to reply. Ahead of him, rocks crunched and exploded in a great shower of dust and debris, sending shards zipping and pinging in all directions. Isaac nearly lost his grip, and the stone he was clinging to tilted violently backwards, leaving him hanging by his fingertips against the nearly vertical surface.