‘Fine. Didn’t she?’ Polly tried to remember. They’d come in, full of the walk and the things they’d seen. Puffins flying onto the ledges of the cliffs. Being dive-bombed by the skuas. Seals. Eleanor had seemed rested, better than she’d been for months. ‘We were all looking forward to the party. It was like being kids again preparing for a night out. She and I sat in her bedroom and painted our nails.’

‘So that would have been a time when she might have confided in you,’ Willow said. ‘When it was just the two of you together.’

‘Yes.’ Polly paused. ‘But she didn’t.’

Willow turned towards Marcus. ‘You haven’t said much, Mr Wentworth. Do you have anything to add?’

‘I didn’t really know her. We met properly for the first time on the boat from Aberdeen. My sense was that she seemed . . .’ He paused. ‘Playful, perhaps. That everything was coming together for her and she was determined to have fun.’

Looking outside, Polly saw that the fog had almost disappeared. It was possible to see as far as the horizon and a milky sunlight was catching the water. She felt a bubble of gratitude to Marcus for bringing the old Eleanor back to life for her.

The younger detective’s phone rang. A ridiculous call sign: the Captain Pugwash theme tune. He blushed and hurried outside with a muttered apology. The rest of them grinned, enjoying the break in the tension. Willow Reeves took one of the biscuits that Polly had set out on a plate.

‘When can we go home?’ Polly asked suddenly. Again she had a longing for her ordinary life, for popping to the local Waitrose for a treat for their supper, and for evenings of theatre or the cinema. For her and Marcus walking along their street on the way back to her flat. Knowing that when they arrived they’d make love lazily and lie in bed afterwards listening to the sounds of the city. That’s what she loved about London: everything was familiar, but anonymous.

‘Whenever you like,’ Willow Reeves said easily. ‘We have no power to keep you here. It makes life easier for us, of course, if you stay locally in case we have more questions.’

‘I’m staying,’ said Ian, pugnacious and determined. ‘For the week that we’d booked at least. Maybe for longer than that. Until we know what happened.’ He hesitated. ‘I can’t stand not knowing. I can live with anything else.’

‘That would be helpful.’ Willow smiled towards Polly as if she sensed her restlessness and discomfort. ‘Of course there’s no need to stay in Unst. Do some trips to Shetland mainland and to Lerwick. After a few days in the sticks it will seem truly metropolitan. A good cappuccino and a restaurant meal and you might not feel so eager to get home.’