In the end he was the one to find it. Willow was craning her neck and looking to the verges on either side, while he kept his eyes on the road. There was a junction with a small track leading off to the left. It would go to Swinning and branch again for Lunna. Near the junction the council had built a lay-by so that folk wanting to car-share could leave their vehicles and catch a lift up to the terminal or into town with someone driving from Brae. There were black skid marks on the main road swerving towards the lay-by. Sandy pulled to a stop, but avoided the tracks. They both got out to look.

‘What do you think?’ Willow was crouching, her nose almost on the tarmac. ‘Was he forced into the lay-by? If it was him?’

‘It looks that way. Or a car pulled out of the track in front of him. With the fog that thick, it could have been an accident. Could have been anyone.’

‘Sure,’ she said.

‘Maybe we should wait. Tape it off and stick a bobby to keep watch until we can get Miss Hewitt back in.’

‘How long will that take?’ She was bouncing up and down on the spot, partly to keep warm because the low cloud was cold, but partly because she was so impatient that she was finding it hard to keep still.

Sandy looked around. None of the hills were visible. ‘Could be a couple of days. The forecast says it’s unlikely to clear until Wednesday. If we hurry, we could get her on this afternoon’s ferry from Aberdeen.’

‘We’re the first people at the scene,’ she said. ‘Our decision.’

‘Aye.’ But he knew the decision had already been taken.

She took it slowly and didn’t rush into it. Plastic overshoes. Gloves on her hands. She didn’t have a full scene-suit, so she found a scarf in the car and wrapped it round her hair. Then she walked backwards and forwards across the empty lay-by.

‘There might have been other vehicles parked there since Friday.’ Usually Perez was the person to council caution while Sandy rushed in with daft ideas. He felt suddenly very grown-up.

‘Over a weekend?’ She looked up and waited for his opinion as if it mattered.

‘Maybe not.’

‘So they could have come from Markham’s car.’ She grinned. ‘He’d have unusual tyres. We’ll be able to check.’

Where the lay-by joined the hill there was a row of whitewashed stones, to stop vehicles running down the bank on foggy days like this. A couple of cars went north along the main road in the opposite direction. Too fast for the weather conditions, Sandy thought. The drivers didn’t even see them because the fog was so thick.