Perez got the call about the discovery just after the afternoon plane had taken off. Stella Monkton had thanked him in her quiet, polite way, before taking her place behind the pilot, but he hadn’t known what she was thinking. On the drive from the North Light to the airstrip she hadn’t spoken. After the birdwatchers had come across the knife, Ben had driven back to the centre to find Sandy, leaving Dougie to stand guard. Now the two detectives were on their own. The light was fading and a steady drizzle had set in.

‘Why did the murderer leave it here?’ Perez said. He was quite certain that this was the weapon that had killed Jane. ‘As you said, it would have been easy enough to throw it over a cliff. Then probably, it would never have been found.’

‘Does it matter? I mean, if it came from the centre they’d all have had access to it. If they manage to get a fingerprint it’ll be: Yeah, I touched it. I helped with the washing-up.’

‘But it was removed from the scene. Not like at the first murder.’ Perez was still haunted by the second murder scene, saw it again, as clearly as a photograph: the body, the stained sheepskins, the tiny white feathers. He’d missed something. Perhaps it was simple – the killer had removed the knife to replace it in the centre kitchen, not sure if its absence would be noticed, if its loss would be traced back to him. Perez tried to picture the route the murderer would take from the Pund to the North Light. The most direct way would be over the hill, but that was heavy going: a steep climb and bog and heather moorland. Much easier to walk to the road past the house at Setter and go north that way.

‘He was scared,’ Perez said. ‘He heard someone coming along the road and didn’t want to be seen. He wouldn’t want anyone to know he’d been so close to the Pund once Jane’s body was discovered. It would be easy enough to hide in the plantation. Then perhaps he lost his nerve. Jittery. The state he was in, he couldn’t imagine walking into the kitchen, rinsing the knife under the tap, putting it back in the drawer. That was his plan but he didn’t have the nerve to carry it out. Though he still had the pillowcase in his pocket. Did he forget about that in his panic?’

‘Or she.’ Sandy was already walking back towards the road. Perez could tell he wasn’t comfortable here in the trees. He wasn’t used to them. Maybe he felt claustrophobic. ‘It could have been a woman. You’re the one who said to keep an open mind.’