‘Here,’ she said. He looked like he might refuse, but eventually took a mouthful. ‘It’s clouding over.’ Siobhan was interested in the sky rather than the view. The clouds were thick and blackening. Funny how the weather could change so suddenly in Scotland. The temperature must have dropped three or four degrees, perhaps more. ‘Maybe a shower,’ she said. Hood just nodded, handing back the bottle.

She looked at her watch and saw that they’d been climbing for twenty minutes. That meant they were maybe fifteen from the car, reckoning the descent quicker than the climb. Peering upwards, she guessed they had another fifteen or twenty minutes to go. Hood expelled breath noisily.

‘You okay?’ she asked.

‘Good exercise,’ he said hoarsely. Then he began climbing again. There were damp patches on the back of his dark blue sweatshirt. Any minute now he’d probably take it off, and be clad only in a T-shirt as the weather turned. Sure enough, he paused to pull the sweatshirt over his head.

‘It’s getting cold,’ she warned him.

‘But I’m not.’ He tied the arms of the sweatshirt around his waist.

‘At least put your cagoule back on.’

‘I’ll bake.’

‘No you won’t.’

He seemed ready to argue, then changed his mind. Siobhan had already zipped up her Barbour again. The countryside around them was growing less visible, either low cloud or mist. Or maybe showers blowing in.

Five minutes on, the rain began. Drizzle at first, and then a smattering of big drops. Siobhan put her hat back on, and watched Grant pull his hood up. It was getting windy, too, gusts cutting across them. Grant lost his footing and went down on one knee, cursing. For the next few dozen steps he was limping, clutching at his leg with one hand.

‘Do you want to wait?’ she asked, knowing what his answer would be: silence.

The rain grew heavier, but in the distance the sky was already clearing. It wouldn’t last long. All the same, Siobhan’s legs were soaked, her trousers sticking to her. Grant’s trainers were making squelching sounds. He had switched to auto-pilot, his eyes staring, nothing at all on his mind except reaching the summit, whatever it took.

As they clambered up the last steep incline, the land levelled off. They’d reached the summit. The rain was easing. Twenty feet away stood a cairn. Siobhan knew that sometimes hill-walkers added a rock or stone each time they ended a climb. Maybe that was how this cairn had come into being.