‘What’s the project?’ Perez felt that he was out of his depth. He knew nothing about the media and only watched TV with Cassie. CBBC or Disney.

‘A film about ghosts. Contemporary hauntings. That’s why she was delighted when I told her the story of Peerie Lizzie.’

‘How did you know it?’ Perez hadn’t realized that anyone outside Shetland had heard of the ghost of Peerie Lizzie.

‘I’m a librarian,’ Polly said. ‘I specialize in folk stories, British myths and legends.’ She paused. ‘Nell never stops working. I guess she’s kind of obsessive. She thought that while she was here she could interview people who’d seen the girl. She even brought a digital recorder with her.’

Peerie Lizzie was a little girl who was supposed to haunt the land around Meoness in Unst late at night. It was claimed she was the spirit of a child, the daughter of the big house, who’d been drowned close by in 1930. The child had been especially precious because the parents had been middle-aged when she was conceived, and some stories had it that her appearance foretold a pregnancy. Perhaps that was why Eleanor had been so interested. Perez was a sceptic. Most people who reported the sightings were young men with a few drinks inside them, or attention-seekers looking to get their name in the paper. As far as he knew, nobody had got pregnant as a result.

He had the sense that Polly was going to say more, but she turned away and looked at the beach, so he resumed the conversation.

‘Do you think she might have wandered up the road last night in the hope of seeing the ghost?’

Marcus appeared with a tray, a pot of coffee and four mugs. Polly waited to answer until he’d set them on the table.

‘It’s more likely than a notion that she would have killed herself.’ A pause. ‘As I said, she was obsessed with the idea of the documentary, so yes, it’s just what she might have done.’ The woman looked up at her partner. ‘Don’t you think so?’

‘I didn’t know her. Not like you did. A couple of supper parties and then a night together when we came up on the boat from Aberdeen . . . But I certainly wouldn’t have had her down as a potential suicide risk.’

‘Do you have a photo?’ Perez still couldn’t get a handle on the missing woman and thought that a picture in his head might make her more real for him. ‘It would help, if we need to widen the search.’ He’d show the boys who worked on the ferry to Yell. If she’d been out early in the morning, and on foot, they’d have noticed her.

‘Not a print,’ Polly said, ‘but there are some on my laptop. I took some pictures on the boat from Aberdeen, so they’re recent. The house has Wi-Fi. Come inside.’

The interior of the house was tasteful and simple. Only the sheepskins in front of the wood-burner and the prints of puffins and gannets on the walls reminded visitors they were in Shetland. And the spectacular view from the window. Polly’s laptop was open on the coffee table and she switched it on. With a few clicks she’d reached the file of photos.