‘I’m not worried about getting in trouble. I mean it, Isaac. Just give it back.’

‘If I come back without it, I will get in trouble.’ A shadow passed across Isaac’s face, as though he’d remembered something unpleasant. ‘I don’t plan to risk that.’

‘I’m not going to let you leave.’

‘I don’t want to hurt you, Alice.’

He shifted his stance slightly, and spread his arms like a wrestler. Alice could feel something change in the air, a kind of thrumming tension, like a guitar string vibrating just on the edge of hearing. She realized he’d taken hold of his threads, leading back to some distant prison-book. A sharp, cool breeze cut through the stagnant air of the library, and the crisp smell of fresh snow briefly overwhelmed the ancient scent of dust.

Alice’s eyes narrowed. No matter how tough he acted, he was still just Isaac. She grabbed the Swarm thread, then hesitated. If she unleashed the little creatures, she really would hurt him, and for all that he was being an idiot, she didn’t really want to. Instead, she drew the thread inwards, hardening her skin, and leaped.

She jumped to the bench, then to the table, then cleared the distance between them with a knee-wobbling leap that brought her down nearly on top of him. Isaac, startled, backpedalled and brought his hands up in front of his face, but Alice went round him instead, grabbing great handfuls of his long coat and yanking him off his feet. He fell heavily on his stomach, and before he could turn over she kept him there by the simple expedient of sitting on the small of his back.

Alice had never had any siblings, so she had no experience with casual children’s scuffles. But Isaac had the disadvantage of a certain amount of built-in chivalry. The kind of person who had saved her from Mr Black, Alice suspected, was not the kind of person who would easily punch a girl in the nose, and while she felt a little bad about taking advantage of that, she told herself it was no worse than his taking advantage of her good nature. Besides, with the Swarm thread wrapped around her, she outweighed him considerably, and the occasional awkward blows he did manage to land simply bounced off her rubbery flesh.

Before too long he’d stopped squirming. ‘Alice,’ he said. ‘Come on, Alice. Don’t be – ow – stop kicking me!’

Alice ignored him and began methodically going through the many pockets in the inner lining of his trench coat. ‘Stop squirming,’ she told him severely. ‘You should have just given me the book.’

After a few more moments of searching, she found a rectangular bulge in one pocket and triumphantly produced the Dragon.

‘Give it back!’ Isaac moaned.

‘Let everyone go,’ she said. ‘Then we can talk to Ending together.’