I couldn't bear to even think about that.
I put my head on my knees, wrapping my arms round them to hug what little heat I could to myself. The cold ached into my bones, but I hardly cared. There was no way of even knowing how long I'd been down there. I couldn't see my watch face, and in the dark I'd lost all track of time.
Huddled and shivering, I strained to hear anything that might indicate help was on its way. Once I thought I did: the echo of a faroff clatter drifted through the cavern. I shouted into the blackness until I was hoarse and my throat hurt. But when I stopped to listen the only sound was the fluid ripple of unseen water.
Feeling as useless as I'd ever been in my life, I closed my eyes and tried to rest.
At some point I must have dozed. I wouldn't have thought it possible, but I was aching and exhausted. Without being aware of it, I drifted into an uneasy sleep.
And then, suddenly, I was awake. For a few seconds I had no idea where I was. Panicking, I narrowly avoided banging my head on the low rock as I started to lurch to my feet. I lowered myself back down on to the cold rock as the bleakness of the situation sank in. My legs had cramped. I stretched out first one, then the other, massaging the muscles to ease them.
That was when I heard the noise.
It sounded like the far-off skitter of a falling rock. I froze, listening. After a moment it came again, and this time it didn't stop. It grew louder, the unmistakable echoing scrape of someone's approach.
'In here!' I yelled. 'I'm in here!'
The cramp was forgotten as I stared into the darkness, relief and adrenalin making my heart thump. It seemed to take a long time before a light appeared in the blackness.
Thank God. 'Over here!'
The light began to move in my direction, the dancing yellow beam of a torch. It was only as it grew larger that I realized it was coming from the wrong direction. Whoever this was they were approaching from the far side of the cavern, not the opening from the mine. And there was only a single light instead of the massed torches of a rescue party.
The shout died in my throat. A sick resignation spread through me as the torch came closer. Beyond the glare I could make out a bulky figure and the pale dome of a bald head, stooped and hunched beneath the bellying rock. It stopped a few feet away. I smelled something rank and animal.
Monk lowered the torch. The filthy combat jacket looked too small across the massive shoulders and arms. The button eyes regarded me as his chest rose and fell, each breath accompanied by a low wheeze.
'Get up.'
The cave system was an underground maze, but Monk seemed to know exactly where he was going. He squeezed through narrow crevices, crawled along water-dripping passages that bent and wormed their way through the rock. He didn't hesitate, slithering through gaps I would never have dared risk by myself. But despite his size he never once got caught or stuck. On the surface he might be a freak; here, in the subterranean tunnels, he seemed in his element.
After that single, terse instruction he hadn't spoken again. Ignoring my frantic questions about Sophie, he'd simply turned and headed back the way he had come, as though he didn't care if I followed or not. Bewildered, I stayed where I was. It was only as the shadows flowed back into the cavern, rushing to fill the vacuum left by the receding torch, that I forced myself to move.
Monk never so much as glanced round, though he must have heard me. I felt utterly lost. None of this made sense, not the fact that he'd come back nor why – or where – he was leading me. The thought of going deeper into the caves appalled me, yet what else could I do? He could have killed me already if that was all he wanted.
And I had to find Sophie.
The passage we were in abruptly opened into a space large enough to stand. Monk started across without pausing. I took the opportunity to catch up.
'Where is she?' I panted.
He didn't answer. He was obviously feeling the exertion, each breath a thick, wet rattle, but he didn't slow. When I grabbed hold of his arm it felt like a piece of teak under the oily cloth.
'What have you done with her? Is she hurt?'
He jerked his arm free. He didn't seem to put any effort into it, but I was yanked off my feet. I sprawled on my hands and knees on the rock, hard enough to skin them.
'Shut the fuck up.'
His voice was a hoarse rumble. He turned to carry on, but doubled up as a coughing fit seized him. He leaned against the rock face, huge shoulders shaking from the violence of the spasm. It sounded as though his lungs were full of fluid as he spat a gob of phlegm on to the floor. Breathing heavily, he passed a hand across his mouth before continuing on as though nothing had happened.
After a moment I went after him. But I was thinking now about the ragged breathing I'd heard over the phone, and the sputum the police had found at Wainwright's house. Everyone had assumed that was a gesture of contempt, but I was no longer so sure.
Monk was ill.
Not that it made him any less dangerous, or slowed him down. I had to push myself to keep up, knowing that if I didn't I'd be left stranded. All I could do was fix my eyes on Monk's broad back, silhouetted by the torch beam, and trust that there was some purpose to this.
I'd been trailing behind him, sloshing ankle-deep through water that ran down the sides of a narrow, upward-sloping passage, when the light suddenly went out. I stopped dead, fighting panic, wondering if all this had been a sadistic trick to abandon me down here.
Then I heard a muted noise coming from nearby, and at the same time made out a faint glow coming from one side of the passage. I edged towards it and found myself at a cleft in the rock. The scrape and grunt of Monk's laboured progress came from inside, and I could just make out the flickering beam of his torch.
The cleft climbed at a steep angle. I had to haul myself up, clambering after the receding light. I went as fast as I could, but it still grew dimmer. The rough grain of the rock scraped against my coat, pressing in closer. Soon I couldn't make out any light at all, or even hear him. I tried to swallow the fear and bile that rose in my throat. Stay calm. Just keep going.
Then the passage kinked in a sharp dog-leg, and I saw a glow up ahead. Following it, I found myself in a small, natural chamber in the rock. I halted, dazzled after the darkness by the dim light from a lantern on the floor. The air was fetid and sour, a mineral dankness fighting with an animal reek. A hissing gas heater threw out a warmth that seemed stifling after the cold of the caves. As my eyes adjusted I took in a jumble of bags, bottles and cans scattered on the floor. Monk was crouched on a rumpled blanket, looking at me with that not-quite-smile and dead eyes.
Huddled as far away from him as she could get was Sophie.
'Oh, God, D-David…!'
She flung her arms around me as I knelt by her. I stroked her hair as she buried her face in my shoulder, feeling her body trembling through her coat.
'Shh, it's OK.'
It was far from that, but the relief I felt at seeing her swamped everything else. Her face was pale and streaked with tears, the bruise still livid. There was something else about her, something that wasn't right, but I was too overwhelmed by finding her to follow up the half-formed thought. She bent her head to wipe her eyes and it went from my mind.
'Are you all right? Has he hurt you?' I asked.
'No, he didn't… I – I'm fine.'
She didn't look or sound it, but I felt my relief edge up another notch. Whatever Monk had in mind, Sophie had fared better than his other victims.