‘I’m sure you do,’ said Sinclair. ‘Besides, John Lowther isn’t dangerous unless he has stopped taking his medication. And even then, he’s only a risk to himself. You say his sister died? The trauma of her death might have disrupted his normal routine anyway. It would be easy for him to slip. I hope he hasn’t gone beyond caring for himself.’

‘Doctor, if John Lowther’s psychotic episodes returned, would the hallucinations be as powerful as they were previously?’

‘Possibly more so. To be honest, in my next consultation with him, I might have been moving towards a conclusion that he was suffering from a treatment-resistant condition.’

‘What would you have done then?’

‘Tried another drug. Probably Clozapine.’ Sinclair took a tissue from a box on his desk and wiped a drop of sweat from his temple. ‘There’s one other thing that might be relevant . . .’

‘Go on, sir.’

‘At the time he was admitted to the unit, Mr Lowther was also suffering from night terrors.’

‘You mean nightmares?’

‘No, night terrors. Nightmares occur during REM sleep, terrors are experienced in stage four sleep. In practice, the distinction is that you remember nightmares, but you don’t remember terrors. They’re subconscious phenomena – but no less stressful, psychologically and emotionally.’

‘And those might have returned, too?’

‘It’s possible.’

‘In John Lowther’s case, would his deteriorating condition be noticeable in the way he talks?’

‘Yes, Mr Lowther suffers from thought disorder, another symptom of psychosis. It can lead the patient to speak quickly and incessantly, or to switch topic in mid-sentence. He could eventually become incoherent, using inappropriate words or mispronouncing them, or making up new words altogether.’

Cooper had been trying to make notes as the psychiatrist talked. But his pen paused, and he looked up.

‘Would you be willing to listen to a tape of an interview we conducted with Mr Lowther, and give us your opinion on it?’

‘Certainly, if you think it would help.’

‘How do you think John Lowther is likely to react in the present circumstances?’

‘It’s difficult to say. He’ll be in a rather unpredictable state. But one thing I’m sure of: he must be a very frightened man.’

‘Frightened of what? Of us?’

Sinclair smiled. ‘Hardly. At the moment, you’re the least of his problems.’

‘What, then?’

He put his glasses down and closed the file. Then he toyed with the items on his desk, teasing them into a more satisfactory arrangement.

‘Most of all, John Lowther will be frightened of himself,’ he said. ‘Of his own inner demons, if you like. Whatever form those demons might be taking.’

‘I don’t understand.’

‘I’m doing my best to explain. You see, Mr Lowther knows about the voices from past experience, though he’ll have tried to suppress the knowledge. If he’s off the medication, his auditory hallucinations will return. They might have returned already.’

‘What will that mean to him?’