The dead riot police were only forty yards away. We could see them clearly now - their padded armor, their helmets with their clear plastic visors showing the cyanotic skin underneath. They moved haltingly as if their muscles had stiffened to pliability of dry wood. Their feet slipped along the ground, looking for equilibrium that seemed in short supply.

"They won't stop," Gary told me. "They won't ever stop."

I hardly needed the information. Ifiyah, the wounded commander of the child soldiers who surrounded me had made the mistake of treating the walking dead like any other enemy force. She had tried to rout them with sustained gunfire from a defensible point. She had thought they would stop, if you gave them a good enough reason. For that mistake she'd been bitten by one of the dead and now she could barely maintain consciousness. Which somehow meant that I was in charge, even if I'd never fired a gun before in my life.

Ayaan fired again and split open a cop's boot. He stumbled and nearly fell but it didn't take him down. The one vulnerable part of his body - his head - was covered by a helmet that the relatively slow round of an AK-47 couldn't penetrate.

I knew that better than anyone. It might as well have been one of the problems I'd had to solve back when I was getting my training from the UN. At seven hundred and ten meters per second, roughly twice the speed of sound at sea level on a sunny day the bullets could impose a great deal of force on those helmets but it would be dispersed by the mesh of Kevlar ballistic fibers lining the helmet. The kind of thing a UN weapon inspector would be expected to know. Whether the target was alive or undead had not been one of the variables we'd ever needed to take into account.

At the west side of the park - our exposed flank, as it were - I heard a shout and looked over to see one of the girls waving at me. I'd sent her there to scout the opposition and the signal meant that we had a horde - a veritable army of the undead - crossing Sixth Avenue, no more than two avenue blocks away from our position. At their standard walking speed of three miles per hour (standard living human walking speed is four miles per hour but the dead tend to drag their feet) that gave us at most ten minutes before we were overrun. Maybe - maybe - we could fight off the ex-riot cops when we engaged them at close quarters but doing so would take time, time we didn't have.

I had nothing to fall back on at that point except my training and so I kept doing the numbers in my head. It didn't matter how pointless my calculations might be.

The ex-police were only thirty yards away when I finally snapped out of it. The girls kept shooting - pointlessly. They weren't prepared for this, not mentally. They were still fighting a guerilla war. Guerilla tactics require an opponent capable of rational decisions. These were animals: no, animals can learn from their mistakes. Only machines persist in the face of their own certain destruction. These were machines we were facing, not people.

I need that, that rationalization, if I was going to shoot them.

The girls had dumped their excess weaponry in a heap at the base of the statue of Gandhi - an irony I ignored for the moment. I'm not sure what if anything I was thinking except that I had better arm myself. The AK-47 I'd been issued back on the boat had a bent barrel, the result of my desperate use of the weapon as a pry bar back in the hospital. I needed a new weapon if I was going to fight.

I had never fired a gun before with the intent of harming anyone. I knew their specs and schematics and statistics by heart but I'd never fired so much as a pistol in a combat situation. I wasn't even looking at the weapon I picked up. I knew in an abstract way that it was a Russian made anti-armor piece, an RPG-7V. I knew that I'd read its user manual before. I knew how to load a grenade in the front end of the barrel and how to hold its wooden heat guard on my shoulder. I knew which hand to put on which of its two grips. I knew enough to take the lens cap off the sighting mechanism and how to close one eye and look through the sight with the other. I lined up the crosshairs with the helmet of the nearest undead cop and pulled the trigger. I knew how to do that, even if I'd never intended to do so as long as I lived.

The dead men were twenty yards away.

A three-foot cone of sparks and fire jumped out the back of the tube and the grenade leapt away from me. There was no recoil at all. I let the now-empty tube fall away from my eye and watched the rocket-propelled grenade disappear at the tip of a column of white smoke. It moved so slowly, seeming to hang in the air. I watched fins pop out of its tail, saw it visibly stabilize itself in midair and correct its tumbling spin. I saw it touch the ground right in front of the leading dead man.

The briefest flash of searing white light got swallowed up instantly by a puff of grey mist that swelled up into an angry sphere of billowing smoke. Debris was everywhere, falling from the sky - broken chips of concrete, divots of grass, a severed hand that smacked dryly on my shoe. A lot less noise than I would have predicted. A hot breeze washed over us, ruffling the girls' headscarves, making me blink away grit and dust. Everything went grey for a second as the expanding shockwave of smoke rolled over us.

The smoke cleared and I saw a three foot crater in the ground surrounded by mangled bodies, limbs torn away, exposed bones pointing accusingly up at the air. A couple of the former cops were still moving, twitching mostly but still hauling themselves toward us with fingers that bent all wrong. More of them lay motionless on the Square, victims of shrapnel and hydrostatic shock.

"Xariif," Ayaan muttered. It meant "clever" and it was the nicest thing she'd ever said to me.

I slung the empty tube, still dribbling smoke from both ends, over my shoulder and waved for our scout to come join us. Time was still very much an issue. Once we had regrouped I lead the girls in a desperate run down Fourteenth Street to the east - toward the Virgin Megastore there. The main entrance, a triangular shaped lobby of glass doors was locked up tight but that was a good thing since it would help keep out the dead. A second entrance near the store's cafe opened when I yanked on the chrome handle of the door. I ushered the girls inside, telling them to fan out and secure the place. Gary brought up the end of the line. I held my arm across the opening before he could go in. We were spooked, tired, and still in a lot of danger. It wasn't going to do much for morale if the girls had to watch Ifiyah die. I wanted to talk to him about what could be done and what our options might be.

"She doesn't have a chance, does she?" I tried, but he was ready for me.

"Let me look at her. Maybe I can save her."

We both knew the likelihood of that. Nobody ever survived being bitten by the undead. The mouth of the dead woman who attacked Ifiyah would have been swimming with microbes - gangrene, septicemia, typhus would have been injected right into her wound. Add in shock and the massive loss of blood and Ifiyah barely stood more of a chance inside with us than outside with the dead.

Still. She was alive, for now. I may have just fired a rocket-propelled grenade into a crowd but it hadn't completely changed who I was. If there was a chance for Ifiyah to make it I had to give her that much.

I sighed but I held the door open for him. He mumbled thanks as he stepped into the gloomy megastore. I followed right on his heels and pulled the door shut behind me.