Well, Dr Forster knew that now, thanks to Rebus.

‘. . . friends I can trust. People need to be told, you see. They censor our mail. They decide what we can read. They won’t even let me read Das Kapital. And they give us drugs. The mentally ill, you know, by whom I mean those who have been judged to be mentally ill, we have less rights than the most hardened mass murderer . . . hardened but sane mass murderer. Is that fair? Is that . . . humane?’

Rebus had no ready answer. Besides, he didn’t want to be sidetracked.

‘You had a visit from Elizabeth Jack.’

Macmillan seemed to think back, then nodded. ‘So I did. But when she visits me she’s Ferrie, not Jack. It’s our secret.’

‘What did you talk about?’

‘Why are you interested?’

Rebus decided that Macmillan did not know of Liz Jack’s murder. How could he know? There was no access to news in this place. Rebus’s fingers toyed with the chessmen.

‘It’s to do with an investigation . . . to do with Mr Jack.’

‘What has he done?’

Rebus shrugged. ‘That’s what I’m trying to find out, Mr Macmillan.’

Macmillan had turned his face towards the ray of sunshine. ‘I miss the world,’ he said, his voice dropping to a murmur. ‘I had so many – friends.’

‘Do you keep in touch with them?’

‘Oh yes,’ Macmillan said. ‘They come and take me home with them for the weekend. We enjoy evenings out at the cinema, the theatre, drinking in bars. Oh, we have some wonderful times together.’ He smiled ruefully, and tapped his head. ‘But only in here.’

‘Hands against the wall.’

‘Why?’ he spat. ‘Why do I have to keep my hands against the wall? Why can’t I just sit down and have a normal conversation like . . . a . . . normal . . . person.’ The angrier he got, the lower his voice dropped. There were flecks of saliva either side of his mouth, and a vein bulged above his right eye. He took a deep breath, then another, then bowed his head slightly. ‘I’m sorry, Inspector. They give me drugs, you know. God knows what they are. They have this . . . effect on me.’

‘That’s all right, Mr Macmillan,’ Rebus said, but inside he was quivering. Was this madness or sanity? What happened to sanity when you chained it to a wall? Chained it, moreover, with chains that weren’t real.

‘You were asking,’ Macmillan went on, breathless now, ‘you were asking about . . . Eliza . . . Ferrie. You’re right, she did come and visit. Quite a surprise. I know they have a home near here, yet they’ve never visited before. Lizzie . . . Eliza . . . did visit once, a long time ago. But Gregor . . . Well, he’s a busy man, isn’t he? And she’s a busy woman. I hear about these things . . .’