Her phone rang. She’d checked it occasionally, but there’d been no signal. It was Marcus, apparently frantic.

‘Where are you?’ Anxiety made him sound almost angry.

‘I’ve just come out for a walk.’ She turned her back on the house where the child might live. ‘I felt locked up in that house. Like it’s a prison.’

‘There’s a murderer out there.’ He was almost stuttering. She was surprised. She’d thought that she suited him because she was so undemanding and had made an effort to be kind to the mother he so obviously worshipped. She hadn’t thought he cared for her so much. Why would he, when everyone adored him. He could choose from anyone She loved him with a passion that took her breath away and shocked her, but had never imagined that the emotion might be reciprocated. ‘You could have put yourself in danger. Where are you? I’ll come and meet you. The detectives want to take your statement.’

She wondered briefly if that was why Marcus was so disturbed: she’d inconvenienced the detectives. But he wasn’t the sort of person to be concerned about that sort of thing. He didn’t usually care what people thought of him.

She told him she would meet him on the road and continued her walk. The next house was much older, dilapidated. The roof was made from turf and she thought nobody could live there. There was an outhouse attached, with broken windows, and the garden was overgrown with long weeds. But as she walked past she thought she saw a white face staring out at her. The glass was so grubby she couldn’t make out any other details, and as soon as she saw it, it vanished. Then she saw Marcus’s car approaching.

Polly didn’t mention her chase across the shore. She would have looked foolish. When she climbed into the passenger seat beside him he took her hand and gripped it tight. ‘You made me so worried,’ he said. ‘Don’t ever do that again.’

He dropped her at Springfield House and said he would wait for her in the car outside; he had a book. Polly thought that he too was finding the atmosphere at Sletts, Ian’s grief and his fury unbearable. It seemed to her that this tall, symmetrical house, so out of place on the bare island, was very similar to the place where Marcus had grown up. He’d taken her there about a month before. She’d expected him to have been brought up somewhere grander than her own parents’ home, of course. She’d imagined a detached house in a leafy suburban street – stockbroker belt, with a local golf course and perhaps a view of the Thames. But his family home was even more distinguished: a small manor house set in a couple of acres of its own grounds, a mini-version of the National Trust properties she’d been dragged to as a child. As Marcus had opened the door to let her in she’d heard her own mother’s voice in her head, the same words that had been spoken at every visit to a new stately home: Mind, lass, this would take a bit of cleaning. Instead there had been his mother, very gracious, offering tea in the drawing room. And as she’d found herself flattening out her accent and taking care not to use dialect words, it had felt like a betrayal, though her parents had always wanted her to get on and would have been as proud as punch to see her there as a guest.