Perez nodded. And again he ran the scene in his head. Markham would have been shocked, and even the new, changed Markham would have been angry. He’d have climbed out of his car shouting and swearing. Anyone would. And Francis Watt, shut off from the real world by the fog, his nerves taut from the waiting and his wife’s endless talking, had lashed out. He’d taken a spade from the back of the truck and hit out.

Perez hadn’t taken part in the interview of Francis Watt. He hadn’t trusted himself to stay calm and professional, but he would have liked to ask how Francis had felt at that point. Had he enjoyed the sensation of power? Was that why he’d decided to kill again?

‘Then what happened?’ It was Sandy again, wanting to move things on. Perhaps he had an appointment in town. A lass to meet, or there were friends waiting for him in a bar, ready to celebrate the end of the case. Perez got to his feet and fetched him a beer from the fridge.

‘They didn’t want to leave Markham there.’ Willow sounded cheerful now. The case was over and she hadn’t screwed up. ‘Soon traffic would be coming back from Lerwick and people would be collecting their cars after work. So they put him in the back of the van. Of course it was Francis’s idea to take him to Aith. The Fiscal’s home territory. An indirect message to the scarlet woman. In the interview Francis told me he thought it would be fitting to set Markham afloat on the water. So they loaded the body into the yoal. He looked in Markham’s briefcase before they pushed the boat into the marina. Of course there was nothing much in there, because there wasn’t much of a story at that point. Just a pile of postcards Markham had picked up from the Bonhoga that morning. Jerry must have posted one to Annabel Grey in Brae when he stopped there for his lunch. Francis took a few of them. Mementos.’

Another indication, Perez thought, that Francis had enjoyed the killing and wanted an object to trigger the memory of it.

‘Late that night they drove Markham’s car to Vatnagarth and then they steamed back to Fetlar,’ Willow said. ‘To make their boats and knit their jerseys and finalize plans for their daughter’s wedding. As if nothing had happened.’

‘But Markham had met John Henderson,’ Perez said. ‘And John suspected that Markham’s murder was connected to the story. The old story of his affair with the Fiscal. I think he’d decided that he had to tell Evie all about it.’