Bannerman concentrated on the road, uncomfortable at the silence, but Morrow was glad to be let alone, her face slack as the warm orange lights of the motorway clicked past on the quiet road. The drive was long and effortless, all the way to Harthill on a smooth and empty road.

Bannerman didn’t know the area they were going to and made a big production of looking for road signs, muttering inaudibly to himself about turns and directions, winding himself up. Morrow said nothing. They took a roundabout, a side road and finally a rough road down the side of open fields with intermittent hedgerows. It had been tarmacked at one time, but a decade or so of harsh winters and tractors had churned the ground uneven. They pulled up outside the perimeter tape.

Blue and white was strung up between some of the hedges, blocking the roadway, and a fat copper was standing next to it, a local plod, warming his hands by rubbing them together and stamping his feet. He wasn’t acting it either; his nose was red and his top lip looked damp.

Bannerman cut the engine. ‘Noisiest bloody car I’ve ever fucking been in,’ he said to himself.

‘Saved us having to talk to each other for forty minutes though.’

Bannerman swung to her aggressively, ready to take it out on her, but found her smiling pleasantly. Despite himself he smiled, swinging away from her so she wouldn’t see him concur. He opened the door and stepped out. She liked him better away from their gaffers.

Opening her own door she stepped out into the bristling cold. Harthill was on higher ground than the city and the air was thinner here, the skies often brutally clear. Tonight a giant white moon lit it. The tarmac on the road had snapped like a slab of toffee. The motorway was hidden behind a hill, the lights glowing over the low horizon. Whoever brought the van here knew the area. Looking to the foot of the hill she saw a clump of wind-gnarled trees gathered around a smouldering white van, well lit by the Forensic Fire team.

The Scene of Crime Forensic team would not be here for a few hours, not until it got light. There wouldn’t be any point in the dark. Unless Osama Bin Laden personally organised a massacre in the Glasgow city centre over the next few hours theirs would be the first crime scene they came to. In the meantime a crew of two were trying to pat out the dying fire, preserving what little trace evidence they could.

It was hard to put out a fire in a vehicle that would serve as evidence. Smother it in foam and you might as well wash it under a tap. Throw water at it and any accelerants would disperse and start an ancillary fire elsewhere. In the morning they’d do a fingertip search of the surround and lift the van without opening it, take it to a sterile environment for analysis.

‘Harthill,’ she said. ‘On their way to Edinburgh?’

Bannerman shrugged a shoulder. ‘Not an obvious place is it?’

‘Maybe they knew it from somewhere.’

‘Can’t exactly make that the basis of a search though can we?’ Bannerman pointed to the ground. ‘No marks.’

She was desperate to know but embarrassed to ask. ‘What else did Omar say?’

Bannerman looked at her curiously, surprised by the tone in her voice, not knowing what it meant. ‘Not much. I thought he was it, but…’

She shrugged and looked off towards the van. ‘I thought he was too.’

Mistaking consensus for intimacy Bannerman leaned into her, quite close, and drew a breath. Suddenly panicked by his proximity she scurried away, over to the fat copper guarding the tape.

He was freezing but still nervous, asked their names and rank and where they were from, jotting it longhand in his notebook, as if he was doing an exam. He probably didn’t have much crime scene experience. He must have been the same age as them, Morrow thought, early thirties, but his ruddy face and fatness made him look much older. People got old quicker in the country.

Sensing Bannerman coming up behind her Morrow ducked under the tape and walked over to the mouth of the field, staying on the far side, away from the obvious path anyone leaving the field would be likely to have taken. A farmer was standing there with a copper but she didn’t look at them. She was looking at the ground.

The moonlight was so bright she could see the shadow of marks in the frost: tyres from a car were picked out in the tarmac, a parked car had sheltered a rectangle from the ground frost and then driven away. She looked up the road, squinted, crouched.

Indistinct footsteps trailing back and forth to the car from the field, muddying one another, some deep zigzagged treads, like army boots, size eightish, some flat soled, like slippers, another pair of trainers. Disappointing: frost was a useless medium for prints.

Bannerman saw her looking at them and shouted back to the plod by the tape, ‘Get the photographer out here and get them before they disappear.’

The plod looked shocked and hurt, as if he had been reprimanded, and swung away to talk into his radio.

She looked away from the footprints and saw the press of tyre tracks. New wheels, clear zigzags and deep lines, which was bad. It was easier to match worn tyres to track marks, chips and wear in the rubber could be as effective as a fingerprint, but factory fresh all looked the same and there were only a few manufacturers.

Bannerman was behind her and nodded at her thought. They traced the movements wordlessly, pointing and tutting and humming, keeping their eyes on the ground. They traced the footsteps to the break in the hedge and looked into the long stretch of churned mud in the field. The footsteps broke up here, the ground was too lumpy, but some of the partial impressions were clearer, a toe, a heel, the side of a sole.

Morrow took what she could from it: three sets of feet coming towards her, muddied by steps that were there already, perhaps meeting others who had been waiting. She looked back, sorting the impressions in her eye: two sets coming towards her, a scuffle of overlaps, but they looked like the same treads on the soles.

Finally Bannerman asked, ‘What ye seeing?’

He was good at this, she knew that, but was either trying to be friendly or intending to steal her ideas for his own. She almost hoped it was the latter. ‘Two gunmen,’ she said. ‘Same boots on. Thought for a minute they were met here but unlikely. Two big men, a driver and a hostage. They wouldn’t all fit in a car unless they were met by just one other guy. Only the army boots go to the driver’s door.’ She pointed back up to the large patch left bare of frost by the car. ‘They must have left a car here to pick up. We can check the CCTV at Harthill, see what pulls off earlier and match it with what pulls out later.’

Bannerman was still looking back at the rectangle. ‘How do you know that’s the driver’s door?’

She drew her finger along the tyre marks. ‘They didn’t reverse out, did they?’

Bannerman looked pleasantly surprised. ‘Hm.’

He was going to steal that, she fucking knew it, he was known for it below ranks. Gaffers thought he was a genius.

‘That’s the third one this year, burnt out cars on my land.’ The farmer standing opposite her was wearing a Barbour coat and had a pissed-off, sleep-puffed face. His accent was almost impenetrable and Morrow found herself watching his lips for clues.

‘Is this your land, sir?’ she said.

‘It is my land, aye, aye, mine, yeah.’

‘Would you mind standing behind that tape over there? We’ve got frosty feet marks here and we’re trying to keep them good until the photographer gets here.’

‘But it’s my land.’

‘Ye can see my point though, eh?’ She gave the copper a look, tipped her head to the side to get the farmer out of the crime scene.

‘It’s my land,’ mumbled the farmer, unsure if he’d been reprimanded, but proactively annoyed anyway. ‘I’m staying here if I want to stay here. And why did you not bother before and now you’re bothering about this one? They’ve burnt out cars before this one and ye did nothing at all. Had to shove the cars out mysel’.’