And then it ended, as suddenly as it had begun. For a heartbeat Alice felt the staggering loss like a physical blow, but after an instant it faded, and the glory of the song dispersed and blew away like a fading dream. She opened her eyes, feeling oddly at peace.

Isaac was bent over her, one arm around her shoulders and the other hand on her chin, his dry lips pressed against hers. His eyes were open, and they locked gazes for a startled moment, before Alice’s hand shot out palm-first and shoved him away so hard he stumbled.

Apparently satisfied, Isaac scrambled to his feet and beckoned. ‘Come on.’

‘But—’ Alice felt like her brain wasn’t quite working. ‘You—’

‘Come on,’ Isaac said.

Alice clambered to her feet, a little shakily. As she turned she saw Mr Black, still standing behind her. Alice had to clamp her jaw shut painfully hard to stifle a scream. His eyes were closed, enormous hands resting at his sides, his mouth half open in awe.

Isaac was already halfway up the staircase.

‘Isaac!’ she hissed. ‘Did you get the map?’

‘I couldn’t find anything that looked like a map,’ Isaac said. ‘Come on, we haven’t got long!’

We have to find it. If they left now, they certainly wouldn’t get another chance, not with Mr Black on his guard. She turned back to the huge, silent figure.

‘He must keep it on him,’ she said. ‘I’m going to check his pockets.’

‘Alice!’ Isaac’s voice was strained. ‘We have to go!’

Alice ignored him and edged up to Mr Black. The top of her head barely came up to his chest, and she had to stand on her toes to get into his side pocket. When she touched him, he shifted slightly, and Alice froze in place like a startled deer. But his eyes were still closed, and after a moment she let out a breath and carried on.

The pocket contained a handful of change and a couple of heavy iron keys. Alice left them where they were and went round to the other side, in spite of another desperate hiss from Isaac. Up close, Mr Black smelled of coal and black smoke, as though he were a furnace himself.

His other pocket held a thick packet of something that crinkled under her fingers. Alice tugged it free carefully, and found herself holding a piece of parchment folded over on itself many times until it was a fat square.

‘Let’s go!’

Alice hurried after Isaac, taking the steps two at a time and slipping past him to open the door into the kitchens. Thankfully, all was still dark and silent, and they ran out the back door and into the night.