Norah was still holding the gun; she could feel the weight of it in her hand. She looked across at Grimm’s lifeless body, rushed over to him and put her hand to his throat to feel for a pulse. It was no more than a gesture. Grimm’s pale face was turned away from her so that she couldn’t see whether his eyes were open or closed. She took a deep breath and realised that she was trembling, but didn’t know whether it was with cold or hatred. She pulled herself up and forced herself to turn back to face the professor.

‘I’ve just killed somebody,’ she said tonelessly.

‘Yes,’ said the professor and Norah saw him bite back a grin. ‘How does it feel? How does it feel to destroy a life?’

‘That’s not how it was,’ Norah shouted. ‘Valerie. And Grimm. The evidence. The guns that kept turning up in my flat…’

She broke off.

‘You’re lying,’ she said eventually. ‘It wasn’t just a self-fulfilling prophecy. It was you! You did this to me! This is your work!’

Balder was silent. He looked as if he couldn’t decide whether to look proud or caught out.

‘How did you do it?’ Norah asked.

‘I didn’t do a thing. You did all this.’

Norah laughed mirthlessly.

‘There’s no point lying to me. I was there. I know it wasn’t me who got hold of the gun. I know there was someone in my flat. I know that Grimm knew Valerie and—’

Norah cleared her throat.

‘I don’t understand,’ she said. ‘He killed Valerie. He—’

She heard Balder laughing softly and broke off again.

‘Do you remember our little talk in Berlin?’ he asked abruptly. ‘Our first talk. In the Adlon.’

Norah stared at him.

‘We talked about magic tricks. You knew that I’d incorporated stage magic into my action art and asked whether I could explain a conjuring trick where someone was made to disappear. Do you remember?’

Norah nodded.

‘I told you the key to every magic trick,’ said Balder. ‘Do you remember?’

‘Distraction,’ Norah replied automatically.

‘That’s right,’ said Balder. ‘All great conjuring tricks rely on distraction.’

He looked at her patiently.

‘I’d told you,’ he said smugly. ‘You should have known.’

‘Valerie—’ Norah began, but Balder interrupted.

‘Everyone has some driving force—an incident, a relationship, a trauma—something that defines them, makes them who they are. And whatever it is, it’s like a lever; once you know what’s driving someone, you have that person in your grip. I didn’t have to dig very deep to find out what was driving you; it was soon obvious that it was the death of your best friend.’

Valerie.

Again, Norah’s eyes drifted across to Grimm’s motionless form. She felt her gorge rise.

‘So this wasn’t about Valerie?’ she said.

It hurt just to say her name.

‘No. Never.’

‘Valerie was only the distraction.’

‘Precisely.’

Balder nodded, apparently amused at her confusion.

‘So, do you mean—’ Norah began.

‘You’re getting there,’ he said encouragingly.