"First we find the drugs," Ayaan said, pointing her rifle at me. "Then we can run." I tried to grab the muzzle and push it away, certain she wouldn't shoot me but she took a deft step backward that left me lunging at air. "They are slow. We have the time, Dekalb."

In the light of just a couple of flashlights I couldn't read her face very well. I could hear the dead men coming up the stairs behind us just fine, though.

I pushed past the girls and into the clinic lobby, my light stabbing through the swirling dust in the corridor. A ward of double rooms stretched to the right - I had no time for this! - to where a nurse's station connected two hallways. Move, I told myself, move, and I broke into a dash. I splashed light across every door I saw. Tub room. Patients' Lounge. Linen Services. Dispensary. Okay. Okay. Yes.

The door had a hefty lock on it, the kind you would need a keycard to enter. With the power out it probably sealed automatically. I ran my hand along the jamb hoping there was some kind of emergency release mechanism and nearly yelped when the door fell open at my touch.

No, I began to howl in my head but I shelved the thought - it didn't necessarily mean anything. Maybe the door automatically opened when the power stopped. I stepped inside the closet-sized room and something crunched under my foot. I pointed my flashlight down and saw a couple of dozen pills in bright orange and dull yellow and that powdery pink so beloved of pharmaceutical companies. Looking up again I saw bare cabinets with their doors hanging morosely open.

To be sure I searched every cabinet with fingers made clumsy by stress. I found a bottle of Tylenol in one of them. Tylenol.

"Looters," I told Ayaan as I raced back around the corner. She just stared at me. "It makes sense - there were patients here, living patients. They couldn't survive for long without their medicine. When they were evacuated they must have taken everything with them." She didn't move. "There are no drugs here," I shouted at her, trying to grab her arm. She shied away from me again.

The sound of the dead coming up the stairwell had grown deafening, their heavy feet smashing down on the metal risers. They would be here any second.

"Is there another room here where drugs will be kept?" Ayaan asked me, "an apothecary?" but I was busy playing my flashlight along the walls of the north-south corridor that lead away from the nurse's station. According to the directory I'd seen downstairs there was another stairwell at the far end of the building and maybe it was clear. Otherwise we were going to have to jump out a window.

"Don't worry, American," one of the girls said. She adjusted the selector lever of her AK-47 and smiled sweetly for me. "We fight them for you."

I pointed my light at her face. Her sixteen year old complexion was marred only at her chin where she had a bad pimple. As I watched in horror a hand trailing strips of torn skin reached around her mouth and pulled her backwards into the darkness outside my cone of light. I heard her muffled scream as the stairwell door swung shut and a noise like a bed sheet being torn to ribbons.

I ran.

Panic surged through me, bubbles of adrenaline fizzing away in my blood as I raced down the hallway. In the dancing light of my flashlight I saw wheeled carts and piles of dirty linen everywhere - I dodged around the former and jumped over the latter and knew for a certainty I was going to break my leg like this but the option, the only option, was to stop and let them catch up with me.

Behind me I heard shots - the rapid buzz of automatic fire. The discipline the girls had shown on the piers had evaporated in the face of a dark hallway full of death. Was it Ayaan, I wondered, or had they already got her? I dashed forward into the dark and pushed open a set of swinging doors to find myself in the other elevator lobby, facing the other emergency stairway.

I looked back. I pushed open the doors and ran my flashlight over the corridor beyond, searched for any signs of pursuit. "Girls?" I called, knowing it would attract the dead but also knowing I couldn't just leave them behind, not if there was a chance of regrouping with them. "Ayaan?"

In the very far distance I heard someone shouting in Somali. She was yelling too rapidly for me to make out any of the words in my limited vocabulary. I listened, craning my head forward as if I could hear better if I could get closer to the sound, but no gunfire or screams followed. Just silence.

"Ayaan," I called, knowing I was alone.

I gave her the time it took me to breathe ten long breaths and then I tried to push open the stairwell door. It resisted so I put my shoulder into it and finally it budged, opening maybe two or three inches. It must have been blocked from the other side. I kicked furiously at it which didn't seem to help at all.

Halfway down the corridor to my right I heard something come roaring toward me. I stabbed out with my flashlight and saw a rolling cart spinning slowly until it collided with a wall. Farther up the passage my light speared a pile of bedclothes, thick with dried blood.

No. Not bedclothes. A woman in a blue paper hospital gown. Dead, of course. Her hair was so fine and sparse it looked like silken threads tied to her mottled scalp. In the yellow flare of my flashlight her skin showed up as a pale green. She didn't have any eyes. I realized in a second what had happened. Coming down the hallway toward me she had stumbled against the rolling cart and fallen to the floor. Even if she couldn't see me she knew I was there. I guess she could smell me.

Slowly, achingly she began to rise to her feet, bracing herself against the wall with one unfeeling arm.

I pushed again at the unyielding door to the fire stairs but it just wouldn't move. I shoved my AK-47 into the gap I'd made and tried to pry open the door. I felt it give a little... and then a little more. The dead woman was on her feet at this point and walking toward me. She was stooped and she walked with a pronounced stiffness in her legs. I kept my flashlight on her all the time as I heaved and heaved against the stock of the rifle. Finally the door sprang open and I saw what had been blocking it - a heavy metal bookshelf. Judging by the bloodstains on the floor of the landing someone had barricaded themselves in the stairwell. Unsuccessfully.

I didn't worry about that. I pushed past it and raced down the stairs and into the hallways of the ground floor. I kept running until I could see daylight ahead through the emergency room doors. I had no idea if any of the girls were still alive but I knew that at that moment I couldn't be of any help to them at all.