‘I wouldn’t have said she was the type. She’d have taken one look at this climb and got back into her Golf GTi.’

‘Except she didn’t have a car.’

‘Good point. So how would she have got out here in the first place?’

Which was another good point: they really were in the middle of nowhere, with towns few and far between and only the odd cottage or farm giving signs of habitation. They were only forty miles from Edinburgh, but the city seemed already a distant memory. Siobhan guessed that few buses came this route. If Flip had come here, she’d have needed help.

‘Maybe a taxi,’ she said.

‘Not the sort of fare you’d forget.’

‘No.’ Yet despite a public appeal, and plenty of photos of Flip in the papers, no taxi driver had come forward. ‘Maybe a friend then, someone we haven’t traced yet.’

‘Could be.’ But Hood sounded sceptical. She noticed that he was already breathing hard. A couple of minutes later, he’d shed the cagoule and folded it, tucking it beneath his arm.

‘Don’t know how you can wear that lot,’ he complained. She pulled the bobble-hat from her head and unzipped the Barbour.

‘Is that better?’ she said.

He just shrugged.

Eventually, on the steeper climb, they were reduced to scrabbling with their hands while their feet sought purchase, the stony soil crumbling and sliding away beneath them. Siobhan stopped to rest, sitting down with her knees up, heels digging in. She took a swig of water.

‘Is that you wabbit already?’ Hood said, ten or so feet above her. She offered him the bottle, but he shook his head and started climbing again. She could see sweat shining in his hair.

‘It’s not a race, Grant,’ she called out. He didn’t reply. After another half-minute, she turned round and followed him. He was moving away from her. So much for team work, she thought. He was like a lot of men she’d known: driven, and yet probably unable to put the reasons into words. It was more in the way of an instinct, a basic need, going beyond the rational.

The climb was levelling off a little. Hood stood up, hands on his hips, admiring the view as he rested. Siobhan watched as he bent his head and tried to spit, but his saliva was too viscous. It hung in a strand from his mouth, refusing to drop. He got a handkerchief from his pocket and wiped it away. Catching up with him, she handed him the bottle.