‘I’m assuming Karen Johnston isn’t a suspect in this enquiry, but a witness?’ McCreadie said to emphasize his point.

That was a step too far for McNab. ‘You can’t assume that about anyone in this case.’

A shocked Marge looked as though she might intervene at this point, but wisely didn’t. As for Magnus, he knew what McNab had just stated was in fact the truth. Children did kill other children. Sometimes on purpose, sometimes by accident.

With that possibility on the table, McNab said, ‘I need to hear everything Karen has to say. And I need to be the one to ask the questions.’

There was silence as McCreadie considered this.

‘What if Professor Pirie and Marge go in first?’ he eventually offered. ‘See how things are with Karen. Then we bring you in, Detective Sergeant?’

‘Before this happens,’ McNab said, ‘I’d like to see the diary.’

‘You can ask Karen for it,’ McCreadie said. ‘She’s got it next to the bed.’

McNab suspected McCreadie had already seen the famous diary, and probably photographed its contents too. After all, he’d had all night to do so.

McCreadie now led them all upstairs. The upper landing proved to be a rectangular balcony with a number of doors leading off. McCreadie chose one and, knocking quietly, said, ‘Karen, Professor Pirie and Marge are here to see you. Is it okay to come in?’

She must have answered in the affirmative, because McCreadie ushered them inside, then indicated that McNab should wait by the open door. ‘You’ll hear everything that’s said from here, Sergeant.’

McNab caught Marge’s voice first. She was greeting her friend warmly, and although he couldn’t see their interchange, he guessed they were hugging. Magnus came next and their exchange was equally positive.

Then he heard Magnus speak.

‘We have my colleague DS McNab with us, who’s keen to talk to you, if you feel up to it. He’s been very concerned for your welfare and has spent many hours, probably without sleep, looking for you. May we let him come in?’

It was a good try on the Prof’s part. McNab had to give him that.

There was a long and silent pause, in which McNab found himself holding his breath. He had every right to walk in, regardless of Karen’s response, but he didn’t want their meeting to begin like that.

She must have nodded, because he heard no words spoken before McCreadie came to usher him inside.

The room was spacious with a big bay window overlooking the green layers of King’s Knot. In the bed a diminutive woman lay propped against the pillows. McNab thought Karen Marshall looked as though a puff of air might blow her away.

Up to now, he’d only viewed the photograph from the recovery cafe where Karen had made a point of disappearing into the background.

He felt an overwhelming sense of relief that Karen Marshall was still alive.

Stepping forward, he offered what he hoped was an encouraging smile. ‘We’ve been very worried about you, Karen. I’m glad to see you’re safe.’