We start our journey two days later, Lisa hobbling along on a pair of hospital crutches I found. We've traded weapons. I wear the rifle and the grenades, while Lisa carries the pistol in a little bag around her shoulders. As well as the gun I'm carrying a backpack stuffed with blankets, food, water and medical supplies. We leave as early as we dare, when the light is only just up in the sky.
Just outside the clinic we stop, and I take a reading from the compass around my neck. Last night we talked about it and decided we would head north, out of the city and into the countryside.
"This way," I say quietly, pointing. "You okay?"
Lisa smiles tightly. "I'll make it," she says.
And so we start to walk. And walk. And walk. All morning we trek down wrecked and rubble-strewn streets. We clamber over piles of brick and steel. We skirt vast craters, eyeing sleeping Creatures with trepidation. At midday we stop to rest in a small dust-coated park, where we sit on the edge of a broken fountain and eat and drink a quick meal from our supplies.
And then, after that short rest it's back to walking. Our progress is slow but steady. I'm faster than Lisa, even with all the weight on my back, even while stopping every few minutes to check we're still on course. But there's very little I can do to help her along. She's not struggling to walk; she's just slow. It's frustrating at first, to be making such limited progress, but as the day wears on and the streets open up onto a more suburban kind of devastation I settle into a steady rhythm.
At times the walking is almost monotonous. We speak little, with Lisa putting all her energy into making progress. And even as we begin to leave the centre, everything is still coated in a sludgy layer of dirt and dust. There's little life to be seen either. At one stage as we're passing through a large park we see a deer come wandering out of the trees, only to freeze at the sight of us, then turn and bolt. Later we catch sight of a trio of figures in the distance. They see us approaching and make themselves scarce long before we get anywhere near.
The only serious scare comes towards the evening, as we're starting to look for a place to stop. At the head of a row of burned out houses we find one that remains intact, and Lisa waits on the road while I go to check it out. I glance in through the windows at the front to see an interior that looks mostly undisturbed, then make my way around the side of the house into the garden. I come around the corner and find myself standing not ten feet away from a Creature.
I freeze. Thoughts collide in my head. It's not dark yet, it's still asleep. Did it just move? Shoot it! Run! I raise the rifle but manage to keep myself from pulling the trigger. I'm staring up at it, staring into the dark holes where its eyes should be, waiting for the slightest sign of life. None comes. I look past the Creature and see that the garden drops away in a sheer cliff just behind it; the edge of a crater.
Slowly, not daring to make a sound, I turn around and walk back to the street. Lisa is waiting for me and I see her open her mouth to ask a question, but I hold up a hand and point down the street. My heart is buzzing against my ribs. I wait until we're a good distance away before I tell Lisa what happened.
She pulls a worried face. "We've not got long before dark. We need to find somewhere."
"We will," I say. "We will."
But every house we pass is too badly damaged to offer secure shelter. We find ourselves in an area where all the buildings are charred down to skeletons, only a few still standing in amongst the destruction. It even still smells of burning, the stink sharp and rich in my nose. The charcoal landscape seems to carry on forever. As the sky darkens the tension in my chest is growing. We have to find somewhere. We have to. Why didn't we just stay put?
And then, in the distance, we hear it. Rising like a siren over the ruins of the city, that terrible hissing, croaking sound.