Annabel didn’t reply directly. ‘We were planning to be married,’ she said. ‘Very soon. We saw no reason to wait. Jerry was going to be baptized, but once that was done, we’d decided to make plans.’ She gave a wide, sad smile. ‘Jerry spent Christmas with us. It was very busy for him at work and he didn’t have time to get home. Dad always goes completely over the top at Christmas. The biggest tree in the universe. Carols round the fire. And this year it snowed. It was quite magical. Walking back from Midnight Mass on Christmas morning Jerry asked me to marry him. It was the best present ever.’

Willow was struck suddenly by the similarity between the two cases under investigation. Both Evie and Annabel were committed Christians marrying an older man. Henderson had been quite different in character from Markham, but the outlook of the women – so certain, so proud of their faith, even in their grief – had much in common. But she couldn’t fathom how that could be a trigger to commit murder.

‘But he hadn’t told his parents about you, even though he missed spending Christmas with them and you’d become engaged?’ The thought had occurred to her as soon as the girl had described the proposal.

‘He didn’t want to tell them on the telephone,’ Annabel said. ‘He thought he should talk to them in person.’

‘Is that why Jerry came to Shetland?’ Perez asked.

It was a simple question, but the girl hesitated. ‘I think he might have told them while he was here,’ she said. ‘That was probably in his mind. But it wasn’t the main reason for the visit.’

‘What was that?’ Perez gave a small and encouraging smile.

And Willow suddenly saw this moment as an epiphany, a revelation that this lay at the heart of the investigation. If they could answer that question, they would find their killer.

Again there was a silence. Outside gulls were screaming. The hoot of a cruise ship leaving the pier.

‘He wouldn’t tell me,’ Annabel said at last, an admission she’d rather not have made. ‘He said there were things he had to sort out before he could commit himself properly to our relationship.’

Willow was tempted to scream at the woman: Didn’t you ask him what he meant? Didn’t you want to know if there was another woman in his life? Some sordid secret? She felt her dislike of Annabel Grey as a fog in her head preventing her from thinking clearly. Why the antipathy? Because of Annabel’s beauty? Her certainty? Her complacency? Her pampered childhood and her doting father?

‘Didn’t his secrecy make you doubt his affection for you?’ Perez asked the question gently, but the answer was fierce and clear.