‘I’ve been thinking about that.’ And it was true. Of all the aspects of the case, this was the one that haunted him most. Sometimes he saw Sarah as a figure like Lady Macbeth, the malign influence behind Fowler, feeding him poison, persuading him with her words and her unhappiness that Angela deserved to die. Had she lured Fran out of the lighthouse, so Fowler could kill her? At other times, he saw Sarah as a victim. ‘I don’t think she was unhappy when Angela died. She was desperate for a child. They’d been through the stress of IVF and then lost a baby late in pregnancy. Angela was pregnant. Sarah was jealous too.’ What a couple the Fowlers must have been, Perez thought. Both of them wrapped up in their disappointment and envy. How did they live their lives? By making small efforts at conversation and normality? Bizarrely, he found himself wondering if John and Sarah ever had sex at the end. There was something almost sensual in the way the women’s bodies had been displayed. Another example of John Fowler’s odd repression?

‘Sarah Fowler knew about Angela’s pregnancy?’ Rhona’s question startled Perez, brought him back to the tasteful room, with the high ceiling and the photographs of old sailing ships on the walls, the immediacy of the investigation.

‘I think so,’ he said. ‘Hugh Shaw claims he heard the Fowlers discussing it. She’d trained as a nurse. And she’d be hypersensitive, wouldn’t she, when she longed so much for a baby for herself?’ He found himself wondering if Rhona Laing had ever wanted a child.

‘Do you know who the father was?’

‘Ben Catchpole,’ Perez said. ‘The timing doesn’t work for anyone else.’

‘I can understand why Fowler killed Moore.’ Rhona reached out and took a piece of shortbread from the white china plate. She seemed disappointed in herself as if she’d given in to a terrible temptation. It seemed to Perez that she had a strange attitude to food. Did she maintain her figure because she was on a perpetual diet or was it all about self-control?

She went on: ‘At least, I can just about understand it as an elaborate act of revenge, conceived by a twisted mind. But he had nothing against Jane Latimer.’

‘That was to do with survival,’ Perez said. ‘It was clear from the beginning that Jane was killed because she’d decided Fowler was the killer. I think she was playing detectives. She liked puzzles.’

‘A dangerous game.’ The Fiscal licked her index finger and scooped up a biscuit crumb from the plate.