Massey looked at them, regarding even Cooper as a complete stranger, intruders he’d never set eyes on before.

‘Do you understand? I was looking into a yawning pit. It was like staring inside my own head. It was black and stinking, and I wanted nothing else except to close the door on it again. Slam it shut, before anything got out.’

‘You convinced yourself Mr Clay hadn’t been there?’ said Cooper. ‘Just in those few seconds when he was out of sight?’

‘I don’t know how long it took. I remember thinking that I must look such an idiot standing there with the hatch open, staring down into the hole. So I looked around me. And of course there was no one in sight, not in that spot. There wasn’t a soul out walking across the moor, not a car nearer than the road, and that was half a mile away.

‘“Well, I’m on my own out here,” I said to myself. And then I shut the hatch. Just like that, without looking down again or saying another word. I just shut it, made sure it fit tight, and I put the padlock back on and shoved the keys in my pocket. And then I walked away.’

‘You left him down there. With no way of opening the hatch, and no hope of anyone coming along to let him out.’

‘Aye.’

‘He had a mobile phone –’

Massey shook his head. ‘Those things don’t work when you’re down inside a concrete bunker. A post like this was built to withstand the blast wave from a nuclear bomb.’

Looking at the man, so calm and matter-of-fact, Cooper wondered for a moment whether they would actually find anyone in the abandoned ROC post, or if this was all just a figment of Massey’s imagination. Was he entirely sane? Had the old man gone quietly over the edge at some point in the last few years, and imagined the whole incident? Clay’s sudden appearance did have a suggestion of wishful thinking – the result of a decades-long desire for vengeance, a hatred so powerful that its object had materialized in the form of a vivid hallucination. They would only know for sure when that hatch was opened.

‘We need to get over there,’ said Cooper.

‘Where is it?’ asked Fry.

Cooper pointed across the fields along the edge of the moor, to the raised area with its line of disused telephone poles. The Toyota’s four-wheel drive came in useful now as they drove round the edge of the empty field to reach the gateway above Badger’s Way.

‘It’s funny,’ said Massey, when he got out and stood by the site. ‘If only there’d been someone out on Black Harry Lane, walking their dog or something, it would never have happened. But I suppose the weather was too bad.’

‘Does this bunker flood?’ asked Cooper suddenly.

‘Oh, yes. It was always a very wet post. We had to pump it out all the time. Now it floods right up into the shaft in really bad weather.’