The housekeeper was there before McNab even reached for the bell. This time Lucy’s expression was sombre rather than welcoming.

‘They’re in the conservatory. I’ve taken through a tray already, Detective Sergeant.’

McNab followed the scent of freshly brewed coffee to find Magnus and Marge seated on the large couch, with McCreadie poised above them in his high-backed chair.

‘Ah, Sergeant. We were hoping you were on your way.’

Magnus cast McNab a glance which he didn’t try to interpret. As for Marge, she appeared genuinely pleased to see him.

Once McNab had his coffee, McCreadie related his story.

‘I was taking my usual walk in the woods by the castle and I saw a woman’s figure ahead of me. There are multiple woodland paths criss-crossing one another on the Back Walk, some much steeper than others. They all eventually lead you to the Old Town Cemetery at the top.

‘The woman was climbing, but slowly, and kept stopping to draw breath. I was much the same. She reached the top before me and I assume went into the cemetery. I took a rest on one of the benches. From there I caught several glimpses of her, threading her way through the gravestones. She was obviously heading for a particular grave.

‘That’s when I realized who it might be. I’d decided to go and check if I was right, when she suddenly came rushing down the slope towards me. I was fearful she might fall, so I stepped out in front of her. That’s when I saw it was Karen Johnston.’

He glanced at McNab as though for permission to go on. McNab remained silent, so he did.

‘She seemed confused and was rambling, but she appeared to recognize me from our encounter earlier on King’s Knot with Lucy’s dog. I suggested I walk her home, since she didn’t look well.

‘It takes a much shorter time to walk down that brae than up, although I feared she wouldn’t make it much further than the foot of the hill.’

McNab interrupted him at that point, his tone verging on the sarcastic. ‘So you steered her towards your house instead of her own?’

McCreadie ignored the insinuation and nodded. ‘Luckily Lucy was here and took charge of Karen. She advised I call my doctor because she thought that a nasty cut on Karen’s arm had turned septic. Dr Wills came and dressed the wound, gave her an antibiotic injection and some painkillers, after which she thankfully slept.’

‘When did all this happen?’ McNab asked.

‘Yesterday evening.’

‘And you only let us know now?’

McCreadie had obviously been waiting for the accusation and was ready for it.

‘Karen begged me not to tell anyone she was here. She appeared very frightened and made me promise. This morning she was more lucid and I got her to agree to meet with Marge and Professor Pirie. She is not aware that I invited you here, Detective Sergeant.’

Being an ex-cop, McCreadie was all too aware that keeping Karen Johnston’s whereabouts from the police could be a punishable offence, but he hadn’t hesitated to do it anyway. The look he fastened on McNab read as: You would have done the same, would you not?