I took a step forward and my hip connected with something hard and square that shot away from me. I heard Ayaan's rifle swing around with a clatter and I brought my light up fast but the thing I'd collided with in the dark was just a rolling cabinet. The halls were full of them. It drifted for a few more feet and then stopped in the middle of the hall. Sheepishly I pushed it out of the way. I could sense the girls behind me - Ayaan and her three squadmates - uncoil as they came down from a tense alert.

For myself I just couldn't relax. I'd never liked hospitals - well, who does? The chemical stink of the disinfectant they use. The desolate utilitarianism of their furnishings. The lingering sense of decay and dissolution. I felt like something was crawling around on my shoulders, one of those long, wet-looking millipedes covered in hairs as fine and curved as eyelashes.

I kicked over a pile of bloody linens, half-expecting something underneath to jump up and bite my leg. Nothing. Ayaan gave me a look and we pressed on. We were making lousy time, by necessity. The hallways of the deserted dark hospital were full of things to trip over, as I had just proved, and every few dozens yards the corridor was broken by a pair of swinging doors. Each of these could hide a crowd of the dead so the girls had developed a strategy for opening them. Two of the girls would kneel down on either side of the doors, their rifles at the ready, their flashlight beams converging on the doors. Ayaan would stand back a few yards ready for a frontal attack. Then I would push on the doors and step back hurriedly as they swung open. Theoretically I could roll out of the way before the shooting started if we found anything. I was pretty sure this was my punishment for not discharging my weapon back on the docks.

We covered a whole floor of the hospital this way. By the time we reached an elevator lobby sweat had soaked through my shirt even though it was cool in the dark corridors and I had a bad facial tic going. Every time we passed a side door that was even slightly ajar I could literally feel my skin trying to crawl off my back. Every time the corridor branched off to the sides I felt like I'd entered an abyss of cyclopean proportions where something horrible and huge might have been lying in wait for years, hoping for just this opportunity to strike.

In the elevator lobby I looked at the signs on the walls, washed out by the fierce bright wash of my flashlight, and tried to figure out what had happened. I knew we were lost, that was perfectly clear. I also knew I couldn't say as much out loud. This was supposed to be my role in the mission, to act as a native guide. Admitting failure at this point might have inspired the girls to head back outside and leave me here alone. Alone and lost, unable to find my way back.

I really didn't want that.

Ayaan cleared her throat. I ran my flashlight over her face, making her eyes glow like glass marbles lit from within. She didn't look scared, which I irrationally felt was some kind of insult to my orienteering skills.

I played the light over the color-coded signs again and then pointed it at the emergency stairwell. "This way," I told them, and the girls stormed the fire door like they were assaulting an enemy fortress. Was I just a coward? I wondered. In my career I had purposefully gone into some of the worst places on Earth (at least they had been before the dead came back to life - now every place was alike in its badness), actively looking for war criminals and heavily-armed psychopaths so I could ask them to pretty please turn over their guns for destruction. I had never felt particularly afraid back then, though I had known when to duck and when to leave with or without what I'd come for. One time in Sudan I'd been in a convoy full of food and sanitary supplies heading to a village in the extreme south of the country. That just happened to be the day the rebels decided to seize that particular road. A hundred men wearing green hospital gowns (they couldn't afford uniforms - they could afford plenty of guns, though) had stopped us and demanded that we just hand over the contents of our trucks. There was some discussion as to whether they should shoot us as well. Eventually they left us with one truck and all of our lives intact and we sped all the way back to Khartoum. I remember my heart beating a little faster then. It was nothing like this, this horripilating dread, this crawling fear.

Back then, no matter how bad things got, there was still some possibility of safety. There would always be a United Nations, and a Red Cross, and an Amnesty International. There were people somewhere who would work night and day to get you released from captivity or transferred to a clean well-run medical facility or airlifted out of harm's way. Since the Epidemic all that was gone. Being a westerner got me nothing here, no help, no relief. Even in the middle of New York I was helpless.

Ayaan and her squad could have sympathized - that was the only kind of life they'd ever known. As we entered the stairwell and started up the stairs I tried not to hate them so much for being so calm.

Clang, clang. Clang, clang. Every step on the stairs rattled and banged with noise. The echoes rolled up and down the seemingly limitless vertical shaft of the stairwell, the sound shivering the cold air that we climbed through. It was loud enough to wake the dead, you know, if they hadn't already been... damn, even dumb jokes couldn't help.

I was scared shitless.

It was some kind of help to me, then, when we rushed the doorway to the second floor and I pointed my flashlight right at a sign that pointed us towards the HIV Care Center. We'd made it. We had nearly reached our destination. Now we just had to grab the drugs and get back out the way we came.

We attacked another door and just like all the others there was nothing beyond it but more darkness and nasty-smelling hospital. More carts on casters and more piles of soiled linen. Nothing moving, nothing voicelessly screaming for our flesh. No sound at all. I took a step into the hallway and saw the reception desk for the Care Center right ahead of me in the yellow stab of my flashlight. I took another step but I could tell the girls hadn't followed. I spun around to demand why.

"Amus!" Ayaan hissed. I shut my mouth.

Nothing. Silence. An absolute lack of sound so distinct I could hear my own breath pulsing in and out of my chest. And underneath that something dull and atonal, and very, very distant. It was getting louder, though. Louder and more insistent.

Clang. Clang. Clang clang clang.

We heard silence for a while. None of us moved. Then we heard the noise come back. Slow, painfully slow but loud. Very loud. Clang, clang. Pause. Clang, clang. Clang, clang.

Something was coming up the stairs behind us.