On his way up the stairs, he remembered what Lucy and Chris had said about the previous owners of the flat. They said they were noisy and difficult to get on with. Not so much hypocrisy as a malicious lie. He could imagine Lucy at work, telling her colleagues how awful it was having to live below Jamie and Kirsty: They put us through such hell; I can’t sleep; I’m sure they do it to spite me. And her colleagues saying, Poor you, poor Lucy.

What were the odds that the Newtons had put the previous occupants of the flat through exactly the same kind of hell they were now inflicting on Jamie and Kirsty? They probably had awful stories to tell about Lucy and Chris. I bet that’s why they moved out, he thought. They couldn’t stand it any more. They gave in.

His heartbeat accelerated. They would be able to back him and Kirsty up. Then the police would have to listen. If Ms Pica and her partner got on so badly with the Newtons, it was unlikely that they would have entrusted them with a key. That was bad news, because it left the question of how Chris had got in unanswered. But it would still be worth talking to them. At the moment, Jamie felt like hardly anyone believed him when he told them about the Newtons. It seemed too far-fetched to be true. But if someone else told the same story, not only would other people have to listen, but Jamie would no longer feel paranoid that he was dreaming all this up.

He knocked on Mary’s door and paced around in the hallway waiting for her to appear. But there was no answer. He knocked again but to no avail. He decided to go up and try Brian and Linda.

Linda opened the door. In her forties, she was still an attractive woman, with pale red hair and bright blue eyes, a striking combination. She conformed to Jamie’s stereotypical idea that male writers always attract good-looking women, beauty drawn to intellect. He couldn’t imagine her behind the counter of Boots. It was a fact that clashed with the other things he knew about her – which wasn’t much, admittedly. Of all the people in the block of flats, she was the one he had had least contact with.

‘Brian’s in his study,’ she said. ‘Come in.’

‘Is he angry with me?’

‘What for? The computer?’ She smiled. ‘He hates computers anyway. Blames them for most of the ills in society. I think he was actually quite pleased when it all went wrong. It proved to him that he was right after all.’ She called out: ‘Brian, Jamie’s here.’

Brian came out of his study, wearing a par of reading glasses that made him look about ten years older than he was. ‘Hi Jamie. Got the day off work?’

‘The whole week, actually.’

‘Very nice.’