‘What are you thinking about, Diane?’ he asked.

‘Henry Lowther.’

‘Not pleasant thoughts, judging by your expression.’

‘I was just wondering …’

‘Don’t keep it to yourself, then.’

‘Well, Brian Mullen said the reason Luanne wasn’t in the house at Darwin Street on the night of the fire was because she was staying at her grandparents’. She wasn’t sleeping through the night, and the Lowthers had taken the child to give him and Lindsay a rest, to let them get a night’s sleep. That’s what he said.’

‘Sounds fair enough.’

‘Mr Lowther didn’t seem to know that, though.’

‘What makes you think that?’

‘Oh, I might be mistaken,’ said Fry. ‘It was only an impression, because of the way he hesitated when I mentioned it. And that was my own fault – I prompted him with Mullen’s version of events, instead of asking him outright. I didn’t think it was important at the time, you see.’

‘Probably it isn’t.’

‘I expect you’re right. Brian and Luanne were the only two members of the family who weren’t at home when the fire started. But it must have been by chance, mustn’t it?’

‘So where do we go from here, Diane?’ asked Cooper.

‘I’ve no idea.’

‘What leads do we have that can be followed up?’

‘None that I know of.’

‘Have we got any clues at all?’

‘No.’

Cooper tipped the last of the water into his mouth and tossed the empty bottle into a bin.

‘We’re really getting on top of this enquiry, then,’ he said.

Fry didn’t react. Let him think she was mellowing with age, if he wanted to. Or that she just didn’t care any more.

‘You know, John Lowther reminded me a bit of that story you told me,’ she said.

Cooper looked round. ‘Story?’

‘The one about the woman who lived in a cottage near your farm when you were a child.’

‘Old Annie?’ said Cooper. ‘Well, I can’t see the similarity myself.’

‘You said she didn’t speak to anyone for weeks on end, then talked far too much when she was in company. As if she had to prove that she could still hold a conversation.’

Cooper looked surprised. ‘Yes, I did say that.’

‘Also, you mentioned finding her frightening. A slightly hysterical tone to her voice, you said. That’s what John Lowther reminded me of.’

‘I know what you mean.’

‘Well, there’s a job for you to do, Ben. I’ll call ahead and get the interview cleared with the hospital.’

‘Hospital?’

Fry explained to him. As Cooper prepared to leave, she listened to the silence of the apartment, well insulated and far enough away from the main road to deaden the sounds of traffic.

‘We’ve got to find John Lowther,’ she said. ‘He could be a lot more dangerous than Brian Mullen.’

Fry dialled the number of the bungalow in Darley Dale, where she had been only half an hour before.

‘Mrs Lowther, where would your son go? What place might he be heading for right now?’

She could picture the Lowthers looking at each other, deciding what answer to give. Fry half expected the phone to be handed to the husband, but it was Moira who spoke.

‘When John wants to be alone, he likes to go up to the Heights of Abraham.’

* * *

An hour later, Dr Alexander Sinclair took off his white coat and put on a suit jacket, transforming himself from a clinical psychologist into a business executive. He sat down at his desk, opened a file and put on his glasses.

‘You appreciate this is very exceptional, Detective Constable.’

‘The circumstances are exceptional, too,’ said Cooper. ‘We wouldn’t have asked you for this information otherwise.’

‘Yes, so I’ve been persuaded by your senior officers. I’m only agreeing to this conversation on the understanding that I’m acting in the interests of my patient, and no further.’

Sinclair peered over the top of his glasses, a mannerism that Cooper hated. It made him look like a disapproving schoolteacher.

‘We’re extremely concerned for Mr Lowther’s safety,’ he said. ‘Not to mention the safety of others that he might come into contact with.’

‘Very well. There are some specific details of this patient’s history that I can’t go into, but I can answer general questions about his condition, which might help you.’

‘Well, we already know that John Lowther spent three months in a psychiatric unit in Leeds.’

‘That’s correct.’

‘Was he sectioned?’

‘No, he admitted himself voluntarily, following a series of psychotic episodes.’

‘What sort of episodes?’

‘Mr Lowther was experiencing auditory and visual hallucinations.’

‘Auditory –?’

‘He heard voices,’ said Sinclair impatiently. ‘And “visual” means he was seeing things.’

‘Thank you.’

He sighed and looked down at the file. ‘At the time, Mr Lowther appeared to be suffering hallucinations of increasing frequency and severity. Admitting himself to the unit was a very sensible decision on his part. He had good insight at that point, so he knew that he was ill.’

‘I’m not sure what you mean by insight, Doctor.’

The glasses came off, making Sinclair human again for a few moments. His eyes were pale blue. He was probably capable of projecting a reassuring bedside manner, when he thought it was necessary.

‘One puzzling feature of psychosis is that the affected individual doesn’t recognize the strange or bizarre nature of his own experiences. Even in the case of acute psychosis, a patient might be unaware that his hallucinations and delusions are in any way unrealistic.’

‘Yes, I see.’

‘However, the level of insight can vary from one case to another. There can be quite good insight in some instances. Of course, this makes the psychotic experience even more terrifying. It means, you see, that the sufferer knows exactly what’s going on. To put it bluntly, he knows he shouldn’t be seeing demons and angels, or hearing voices – but he sees and hears them nevertheless. He can’t stop himself. Try to imagine being aware that you’re not in control of your own mind any more. You’d have to accept that some of your everyday perceptions are real, but others are illusory.’

‘It’s difficult to put myself in that position.’

‘Of course it is. Believe me, when a patient is aware that he’s losing control of his own thoughts, it strikes to the very core of self-belief, and can have an extremely destructive effect on his relationship with the world around him. It undermines the concept of identity, you see. I can imagine nothing more devastating, or more terrifying.’

Sinclair put his glasses back on and peered at his visitor, assessing his reaction. Cooper was surprised by his sudden departure from the script, or rather from the notes in his file. For a few seconds, he’d spoken with real conviction. It struck Cooper that Alexander Sinclair had actually seen this happen to people he knew well – not just patients, but friends or family. Perhaps that was why he’d agreed to talk, despite the constraints of confidentiality.

‘Can you tell me what John Lowther’s auditory and visual hallucinations consisted of? Is it possible to say?’

‘In general. He heard voices that commented on his behaviour, and told him to do certain things. That’s why he admitted himself. He was frightened of what the voices might make him do, and he wanted us to stop them.’

‘And did you?’

Sinclair smiled. ‘Psychosis is only a symptom of mental illness, Detective Constable. The subsequent diagnosis was bipolar disorder. Mr Lowther was treated with anti-psychotic drugs until the episodes receded, and then we adjusted his medication until he was stable enough to be discharged.’

‘So the medication made the voices go away?’

‘Well …’

Cooper watched him hesitate.

‘But only as long as he kept taking the tablets?’ he said.

‘Of course. Anti-psychotic drugs work by changing the activity of chemicals that transmit messages in the brain. It’s very important to take the medication regularly, and at the prescribed doses.’