‘No worries about that,’ she said. ‘I always sleep well.’ And she disappeared up the dark staircase, her heavy holdall on her shoulder. He’d offered to carry it in to the hotel for her, but she’d stared at him as if he were mad.

The next morning she was in the police station before he was. She’d tied back her hair, but it still looked untidy and she was wearing the same shapeless jumper. She looked up from the desk they’d found for her in the small office that Perez had once used. A mug full of something that smelled herbal and looked like piss stood on her desk.

‘I’ve tracked down Markham’s mobile-phone provider,’ she said. ‘I got his number from his parents. There seems to be some problem – maybe he recently got a new number – but they’re trying to find it for me. It’s too early for news from Aberdeen on the postmortem.’

‘I’m going to head out to Vatnagarth,’ Sandy said. ‘I checked the council website and the museum’s open this morning.’ He always preferred to be out of the office. Here, he had the sense that people were looking over his shoulder, judging his work.

‘Sure,’ Willow said. ‘Whatever you think.’ Her attention had already been caught again by the screen in front of her.

In the copse of sycamores there seemed to be birds everywhere and the sun was bright as he approached the museum. A people-carrier was parked outside, but Markham’s car had been removed. It would be taken south to Aberdeen on the ferry. The crime-scene tape had disappeared too and there was no sign that the police had ever been interested in the place.

There was smoke coming out of the chimney, so everything smelled of peat. The door was open and he walked into the tiny space that separated the but-end of the house from the ben. To his left another door led into a living room. The window was so small and the walls were so thick that there was very little light. He struggled to make out if anyone was there. Then he saw a large woman wearing a skirt that looked like sackcloth and a knitted jacket. The sort of clothes he’d seen in photos in his grandmother’s house, so he wasn’t sure for a moment if she was real or a kind of manikin. She was sitting on a Shetland chair close to the range. He felt that he was stepping back in time, into one of his grandmother’s photos. Then the woman moved; she was feeding carded fleece into a spinning wheel.

‘Welcome,’ the woman said. ‘Come in.’ He had the sense that he’d seen her before, very recently, but he couldn’t quite remember where. ‘Look around at whatever you like and give me a shout if you have any questions. There’s a booklet on the table.’