He put a photograph of Evie Watt on the table in front of her. It wasn’t the one they’d used on the board here in the incident room, and Willow wondered where Perez had found it. It had been taken at some Shetland Island Council function and Evie was smartly dressed in a skirt and a jacket, looking oddly grown-up. Willow had only ever seen Evie in jeans before.

‘Brian thought this might have been the woman who met Markham the morning before he died.’

‘Is he sure?’ Willow remembered the young woman on the beach in Fetlar, her anger and her grief. Surely her judgement couldn’t be that flawed. Evie Watt was no killer.

Perez shrugged. ‘Brian’s a reformed junkie. He’s never been sure of anything.’ He paused and was about to continue when Willow broke in.

‘Hardly a star witness then. I’ll need more than that, Jimmy.’ She waited for him to continue, to defend his position, but Perez just shrugged again. He’d become moody, the man she’d first met when she arrived on the islands. She’d made this man coffee, bent over backwards to be pleasant to him and he behaved like a graceless and uncommunicative teenage boy.

‘Anything else?’

‘I went past the track to Evie Watt’s croft yesterday afternoon. Where you found John Henderson’s body. They’ve turned it into a kind of shrine. Flowers, candles, you know.’

She nodded.

‘I found this there.’

It had been on the table all the time, but she’d been focused on Evie’s photo and she hadn’t noticed it. The postcard in the clear-plastic evidence bag. He slid it towards her. She turned it over. Nothing written on the back.

‘It’s the same as the one Jerry Markham sent to Annabel,’ she said. ‘There were others in his briefcase next to the body.’

‘There’ll be hundreds of them floating around Shetland,’ Perez said. ‘They were handing them out free in the Bonhoga. It could mean nothing.’

But she could tell that he believed it was more important than that. ‘If it had come loose from a bouquet or a gift, surely it would have a message on it,’ she said.

‘That was my thought.’

‘So, Jimmy, what conclusion have you come to? What was this thing doing there?’

‘The killer could have taken it from Markham’s briefcase.’ His voice was quiet, tentative. Was he worried that she would mock him for his ideas? Surely he must know her better than that.

‘A trophy, you mean?’ She frowned.

‘Or a memento.’

‘And then he left it at the place where John Henderson died. Why would he do that?’ Willow was struggling to understand this.

‘I don’t know. To link the killings. As a sign? A message?’

‘Who to?’ Perhaps Perez is crazy, she thought. Perhaps he was right when he said he was mad.