‘Macho Man!’ someone sang.

‘What do you want?’

There was a small white caravan hooked up to an antiquated Land Rover. She’d opened the caravan door – just the top half – and was leaning out.

‘Can you smell the bacon, Jo?’ the guitarist asked.

‘Need to talk to you, Joanna,’ Rebus said, walking towards the caravan, ‘about Mitch.’

‘What about him?’

‘Why he died.’

Joanna Bruce looked at her fellow travellers, saw that Rebus had their attention, and unlocked the bottom half of her door. ‘Better come in,’ she said.

The caravan was cramped and unheated. There was no TV, but untidy stacks of magazines and newspapers, some of them with articles clipped out, and on the small folding table – benches either side, the whole thing convertible into a bed – a laptop computer. Standing, Rebus’s head touched the caravan roof. Joanna shut down the computer, then gestured for Rebus and Jack to take the bench seats, while she balanced atop a pile of magazines.

‘So,’ she said, folding her arms, ‘what’s the story?’

‘My question exactly,’ Rebus replied. He nodded towards the wall behind her, where some photos had been pinned for decoration. ‘Snap.’ She looked round at the pictures. ‘I’ve just had another lot of those developed,’ Rebus explained: they were the originals missing from Mitch’s envelope. She sat there with a face like stone, giving nothing away. There was kohl around her eyes and her hair was white fire in the glow from the gas lighting. For a full half-minute, the soft roar of igniting gas was the only sound in the caravan. Rebus was giving her time to change her mind, but she was using that time to erect further barricades, her eyes closing to slits, mouth pressed shut.

‘Joanna Bruce,’ Rebus mused. ‘Interesting choice of name.’ She half-opened her mouth, closed it again.

‘Is Joanna your real first name, or did you change that too?’

‘What do you mean?’

Rebus looked at Jack, who was sitting back, trying to look the part of the relaxed visitor, telling her it wasn’t two against one, that she’d no need to be afraid. When Rebus spoke, he spoke to Jack’s face.

‘Your real surname’s Weir.’

‘How … who told you that?’ Trying to laugh it off.

‘Nobody needed to. Major Weir had a daughter; they fell out; he disowned her.’ And changed her sex to a son, maybe to muddy the water. Mairie’s source had said as much.

‘He didn’t disown her! She disowned him!’

Rebus turned to her. Her face and body were animated now, clay come to life. Her fists gouged at her knees.

‘Two things put me on track,’ he said quietly. ‘One, that surname: Bruce, as in Robert the … as any student of Scottish history would know. Major Weir is daft on Scots history, he even named his oilfield after Bannockburn, which as we know was won by Robert the Bruce. Bruce and Bannock. I’m guessing you picked the name because you thought it would rile him?’