The story Karen had told McNab of what had really happened that day – the switching of outfits, Karen taking Mary’s place at the altar to be confirmed – did ring true, because it answered many of the questions they’d had. Rhona had gone over the sequence of events using Karen’s story and for the first time it seemed to her that they fitted. It’s what had happened afterwards that still had to be made clear.

The killer had taken possession of the bag, so he’d visited the den after Karen’s departure. Had he known Karen would return to change and had he been watching for her? Maybe he’d intended to also take Karen?

Rhona wondered if Karen had considered this afterwards, and fear at this happening had kept her silent?

The shaded drawing and what it had revealed showed that Karen had been afraid of Alec McLaughlin, who’d taken to sitting on the hill watching them play tennis, while shouting obscenities. Her father had warned her about bad men. Karen had puzzled over whether she knew of any bad men, then thought she knew one.

Was she thinking about Alec at that point or someone else?

As for the jumper story, that too had rung true. She could only hope that they would recover something from it that might give them a lead to Mary’s killer.

For once Chrissy wasn’t at the lab before her. Rhona had a silent wish that it was because Chrissy had stopped to pick up their filled rolls on the way. As she thought this, she noted the row of porridge pots staring down defiantly at her from the shelf near the coffee maker. Rhona assured them their days were numbered as she set about making the coffee.

Chrissy entered shortly after, accompanied by a delicious smell, signifying that Rhona’s wish had just come true. Trying not to gloat at the porridge pots, Rhona acted as though this was simply normal.

‘Coffee’s ready,’ she announced as Chrissy plonked the two brown paper bags on the table.

‘Full works,’ Chrissy promised.

Once settled and eating, Chrissy said, ‘Where did you disappear to last night? When I came back from my rounds, you were gone,’ she added accusingly.

‘Ellie arrived when McNab and I were talking. I was avoiding what looked like a possible fight.’

‘Wise move,’ Chrissy agreed. ‘And here I thought you’d ducked out before Dr Walker arrived. Remember how you invited him?’

‘Oh God, did he come?’ Rhona said in horror.

‘Of course, and he spent a lot of time looking for you. I was no help, since I didn’t know you’d left,’ Chrissy said. ‘Looks like you’re on a run of standing men up.’

Rhona had completely forgotten about inviting Richie, but she could hardly tell him that.

As though reading her thoughts, Chrissy said, ‘I’d like to be a fly on the wall the next time you two meet up.’

‘I went home early to read Karen’s diary,’ Rhona said. It was an excuse, but a real one. ‘McNab had photographed it and sent it through, along with a recording of his talk with her.’