Cooper stood quite still and listened, straining his ears for the slightest noise. After a few moments, he became convinced that he was only imagining things, creating voices where there weren’t any. It was another effect of the fog, producing sounds which weren’t really sounds at all but the components of silence. It seemed to him that he was hearing an echo, but without the noise that should have preceded it.

‘Do you think Jack Elder is still here in the mine somewhere?’ said Fry.

‘If not him, then someone else that he came to meet,’ said Cooper. ‘That banging sounded like a signal to me.’

At that moment, a figure appeared ahead of them, catching the light from their torches and throwing a vast, distorted shadow on the wall of the engine house.

‘Can you see who it is?’ whispered Cooper.

‘Yes,’ said Fry. ‘It’s PC Bloody Palfreyman. And he’s carrying a shotgun.’

From his position on the mound, David Palfreyman heard the voices, but couldn’t locate them in the fog. He stepped quickly behind the winding gear, bringing the shotgun up ready.

Two of them, at least. That was pretty much as he’d expected. He could take two out easily, one with each barrel. And he’d be sure of killing them, if he got close enough. Or make a nice mess of them, anyway, if he couldn’t.

The fog should help him. And this maze of ruined buildings and the mountains of spoil made it easy to slip out of sight at any moment.

He’d known they would come, had judged them just right. He hadn’t lost his old instincts. No one came on to his patch and treated him like that. There were different forms of justice, and some were more final than others. Tonight, they would find out everything they needed to know about his form of justice.

It was only when the light of the torches hit him that Palfreyman realized he’d exposed his position. Had they recognized him? It didn’t matter. He knew this place better than they did, and he could be among them before they got anywhere near their car.

Palfreyman laughed quietly to himself. Poor sods. They thought they were the kings around here now. Some of them thought they were pretty clever. But they’d pissed PC David Palfreyman off, and they had it coming.

He slithered down the east side of the mound and ran to the corner of the winding house. He could see them now, trying to keep low, scrambling towards a vehicle parked in front of the agent’s house.

Cooper and Fry had taken cover at the base of the square chimney, where the roof of the flue had collapsed. There was no more cover left between here and the car. They would have to cross the track and yards of muddy ground churned by cattle before they got anywhere near it.