Mary sniffed. ‘Remember the huge sea snake we saw after we got to the shore? That was Crows. He knew at that point that the portal was probably somewhere on the island. When he couldn’t find it, he got me to tell him exactly where. They’re not supposed to disappear.’

Bell suddenly showed more than passing interest. ‘The portal vanished?’

‘There’s nothing but rock there now. It’s gone, and Crows didn’t know what that meant. Do you?’

Bell shook her head. ‘Portals are attached to London. They don’t go anywhere. They’re fixed points.’

‘What if,’ said Dalip. ‘What if London ceased to exist?’

That caused disquiet, but he persisted.

‘I don’t mean to … I’ve got as much to lose as everyone. But that fire wasn’t normal. We ran and ran, and it wasn’t enough. Even a plane crash wouldn’t have been that bad. And if – I don’t know – a nuclear bomb, maybe, with a firestorm afterwards. Would that be enough to break the connection?’

‘When are you from?’ asked Bell.

They were all too surprised at the question to answer, except Mary.

‘Twenty twelve. You?’

‘Nineteen sixty-eight.’ Bell looked at them again, each one, checking for differences between them and her. ‘How did it go, those forty years?’

‘Good for some. Not so good for others,’ said Mary. ‘This is well off the point, though. Crows said that whoever controls the portals, controls Down.’

‘And London,’ said Dalip. ‘They’d control London too.’

‘That. But no one’s ever managed to open a door going the other way, right?’

‘No. But there has to be a way to do it.’

‘Why?’ asked Mary. ‘Why does there? Why can’t this just be it?’

‘Because it doesn’t make sense otherwise. If things can pass from London to here, then it stands to reason they can pass back.’

‘You mean like you can turn into a dragon and fucking castles grow out of the ground?’

Bell faltered. ‘This place just has different rules, that’s all.’

‘One of which might be, you can’t go back,’ interrupted Dalip. ‘Do you have any evidence at all that anything has ever gone back to London, over and above simply wishing it was true?’

‘No,’ she whispered. ‘No.’

‘Great.’ He turned away, then abruptly towards her again. ‘You were going to have me fight people to the death because you hoped something might just happen that had never happened before. That’s just …’

‘Fucking nuts?’ offered Mary.

‘Pretty much covers it. If you were going to experiment on someone, at the very least you should have started with yourself.’ The wind rattled the balcony doors open, and Dalip went to close them with something more substantial.

‘These maps,’ said Mama. ‘Are they that important?’