‘I’m not sure I ever understood her.’ Stella Monkton’s eyes were drawn to the garden just outside the window. It had been surrounded by a wall to provide shelter from the wind, but everything there had been ruined by the previous week’s storm. She seemed particularly fascinated by the row of sprouts, blackened by the salt spray, flattened. ‘And I didn’t like her very much. But occasionally there were moments of kindness and humour, a sudden vision of the girl she might have been in different circumstances.’ Stella corrected herself. ‘If I’d behaved differently.’

‘How could you ever know what she might have become?’ Perez said. ‘Nature and nurture. An old argument.’

‘In either case, surely, I was partly responsible.’ She gave a wan smile. ‘After Angela completed her PhD all contact stopped. It was as if I’d never existed.’

Perez didn’t know how to respond. It wasn’t what he’d been expecting. He felt an ache of sympathy for the woman. She’d thought she had her daughter back – even if Angela wasn’t the daughter she might have chosen – only to lose her again.

‘Was there a row?’ he asked at last.

‘Nothing like that. Perhaps it was what she’d planned all along. Revenge. To drop me as I’d abandoned her. Perhaps she just felt she didn’t need me any more. After all, her disappearance from my life coincided with her success: the discovery of a rare bird on one of her travels, a best-selling book. The television series followed soon after.’

‘Did you try to get in touch with her?’

‘Of course. By email and by phone. But she didn’t reply and I knew there was no point in persisting.’

‘Then she married.’ Perez thought of his mother, the fuss she was making about his second wedding. It seemed a child’s wedding was a big deal. ‘Did you know about that?’

‘There was a note about it in a natural history magazine I was reading at the dentist’s,’ Stella said. ‘It had already happened by then. I certainly wasn’t invited.’

‘But you knew she’d taken up the position of director at the Fair Isle field centre?’

‘Occasionally I’d Google her,’ Stella said. ‘It was one way of keeping track. The field centre has a website. There was a picture of her next to the lighthouse. She looked very happy.’ She was staring into the distance. ‘I did think of booking myself in as a visitor. Perhaps using a made-up name. But really I had no right to intrude where I wasn’t welcome.’

Perez was astonished by the woman’s restraint. He tried to imagine Fran in a similar situation. She wouldn’t consider the niceties of her daughter’s feelings – she’d be on the first plane north. But Fran hadn’t run away and left Cassie behind.