Whereas before I was at least able to make out the shapes of cars and people in the dark, now I can see nothing. Not a thing. Even the hand I hold out in front of me to feel my way is invisible. If I was to let go of Sharon's hand I don't know if I would be able to find it again.
We slow to a walk as we reach the bottom of the ramp. I can sense people moving in the darkness around me, all of them stumbling blind and without a clue. There's the sound of someone crying, someone else calling out for help. And underneath it all the sounds from the level above keep drifting down to us: the screams and the awful meaty sounds of butchery.
"Just keep walking straight," I whisper to Sharon. "We'll find a wall eventually."
That's what we do. It's unnerving, walking into the dark like that. I keep one hand wrapped up tight in Sharon's, and the other raised in front of me, feeling my way like a blind man. My imagination is working in overtime, imagining me walking over the edge of a pit, into the arms of a waiting maniac. But I carry on walking anyway: anything to get away from what's happening up there.
My hand touches something cold and metallic, and for a second the shock of it makes me catch my breath. But then I realise it's just a car. One of hundreds that must be parked down here in the blackness. I take Sharon's arm and we skirt around it, then carry on in the same direction we were walking before. A minute later and we reach a wall.
"What now?" says Sharon. We put our backs to the wall and look in the direction we came. No matter how much I strain my eyes I cannot see a single thing. There's only the noises to keep us company. Sharon's shivering. Whether with fear or cold or shock I cannot tell.
"Now we hide," I say. "We hide and wait until it's safe."
We crouch down against the wall. I wish I could block my ears against the sounds that are still filtering down to us from above, but to do so would mean letting go of Sharon, and I'm not about to do that. So we hold each other tightly, and endure it together.
I find my mind wandering, my imagination making more unwelcome suggestions. I picture escaped zoo animals running wild in the broken city, lions and tigers and wolves preying freely on whatever helpless pockets of humanity they find. I picture gangs of escaped criminals, driven inexplicably mad, slaughtering just for the fun of it. I picture the foot soldiers of an invading army, sent in to clear out any survivors with guns and knives and fists. Even thinking these things makes my gut feel cold and shrivelled. I hold Sharon tighter.
Please, I think, please let us live through this.
Just then I become aware of something. There's a soft, slight breeze playing down the side of my body. The source of it feels close. I reach out and run my hand along the concrete wall against which I'm sitting. Sure enough, not an arms-length away from me, my hand encounters wood, smooth and cool and not quite flush with the wall. It's a door. A fire exit.
"Quick," I say to Sharon. We scramble to our feet and I feel my way along so that I'm standing in front of the door. After a few fumbling seconds my hands find a wide metal lever. I push down, there's a creak, and I feel the door swing open towards us. I grab Sharon and pull her through. The door slams shut behind us, mercifully cutting off some of the noise.
We're still submerged in darkness, but the space feels smaller. Our footsteps don't echo like they did in the main car park.
"What's going on, David," whispers Sharon. "Where are we?"
"It's a fire exit," I say. "It must be. Listen, Shar, I felt a breeze. That must mean this leads outside. We just have to find the stairs..." I'm moving as I talk, feeling my way around the small space in which we find ourselves. Sure enough, at that very moment I stumble on something hard, and the sharp edge of a stair smacks into my calf. Relief accompanies the pain. "Over here," I say. "Come towards my voice."
Within a minute me and Sharon are making our way slowly upstairs in the dark, clinging to the handrail all the way. One flight, then two, our breath becoming laboured as we climb. And then there are no more stairs, and we're facing a door. I can just about make it out in what dim light there is now. A green fire exit sign is tacked to the wall beside it.
I reach forward, grab the handle and push down. The door swings open. Fresh air rushes in to greet us, heavy with the stink of smoke. We step out into the bitter night. The sight that greets us is far, far worse than anything I could have imagined.