But then again, if he was that shite at reading people, why was he a detective?

‘So,’ Janice was saying, ‘I’ve taken a look at last night’s crime scene. Pretty rough.’ She made a face. ‘Are you planning on attending the autopsy?’

‘Not my responsibility,’ McNab said firmly. ‘I was only called in to identify the victim and because he was one of our suspects.’

‘Any thoughts on who did it?’

‘Let me count the possibilities.’

‘What if it was our killer, because McLaughlin knew too much?’

‘If it was, then we’ve rattled somebody’s cage.’

They’d continued with their enquiries with respect to other known paedophiles and child murderers across the UK. There were plenty who would have fitted the timing, including the notorious Robert Black. But the consensus among the team was that this had been local. McLaughlin’s demise might be a further signal that they were right.

McNab told Janice about the blue sweater. ‘There’s no guaranteeing it was Mary’s, but I called on Jean Barclay last night and she thought it might be. According to Jean, her mother knitted a blue one for Mary and a maroon one for her.’

‘Karen Marshall could provide the answers to a lot of this,’ Janice said.

‘If we find her.’ McNab didn’t add ‘alive’, although that’s what they were both thinking. ‘Rhona reckons the wound in the kitchen could have been self-inflicted,’ he added.

‘So she may be in danger from herself as well as someone else.’ Janice glanced at her watch. ‘The Prof’s bringing in Marge from the recovery cafe to speak to us about exactly that.’

They went via the coffee machine. Armed with a double espresso, McNab held the door open for his partner to enter first, which resulted in a strange look from Janice and a whispered ‘Stop it.’

Slightly rattled by this, he wondered if he’d never done it before. The truth was, he had no idea.

Magnus rose on their entry and shook both their hands, before introducing the woman who sat next to him as Marge Balfour, from the Raploch women’s recovery cafe.

McNab examined the formidable-looking woman, who was also eyeing him up with the same interest.

‘I’m not o’er fond of the polis,’ she declared. ‘But the professor tells me I can trust you,’ she told McNab.

‘We all want to find Karen,’ Janice said. ‘Anything you can tell us with respect to that, we’d be very grateful.’

The firm set of Marge’s mouth eased a little. ‘I take it he’s your partner?’ She gestured to McNab.

When Janice nodded, she said, ‘If you can trust him, then I suppose I can.’

That settled, Janice set up the recording, then asked Marge to tell them everything she could about Karen.

It was a sorry tale, interspersed with hope. She spoke of Karen turning up at the recovery cafe, like a waif and stray. How the women had welcomed her but hadn’t hounded her about her reasons for being there.

‘She’d been on the drink,’ Marge said. ‘Although not on that day. She looked more like she could have done with a drink.’ At this point she eyed McNab, as though reading him like an open book. ‘She eventually told us about her man, Jack, and the dementia. Christ, anyone who hasn’t seen that fucking awful illness in action has no idea the way it hollows you out, you and the folk caring for you.’ She paused. ‘The drink had got her through it, but she’d stopped that before coming to us. “Jack told me to,” she said.