The next section of the vent extended for what felt like about sixty feet before it dead-ended. I shuffled backward again, feeling the walls for turnoffs that I might have missed. There was nothing but solid, unyielding metal. I took a deep breath and held it until the panic that had been starting to writhe in my belly died down. If I had to go back, I’d go back. There were no pits between me and the last turn. It would be hard. It wasn’t impossible.

A faint breeze ruffled my hair as I prepared myself for backing up. I stopped. Then, cautiously, I lifted one hand above my head.

First it hit the metal roof of the vent. And then it hit nothing but empty air. I had found the ventilation shaft.

“Okay,” I whispered. “I can do this. I can do this. It’ll get me home.” I squirmed forward again, until I could roll onto my back and reach up into the open ventilation shaft with both hands. It was square, rather than rectangular, and slightly narrower than the main vent. I would still fit, but it was going to be a tight squeeze, and I was much more likely to find myself stuck. I could die in there.

It would still be better than staying here with Sherman. I dug my fingernails into the joins between pieces of metal and began pulling myself up, bracing my feet and knees against the sides of the shaft for traction. All those laps around the mall were really paying off. Now all I had to do was hope that I would reach the top before my strength gave out completely, and that whatever was between me and freedom would be something I could easily move aside.

I didn’t know how good security usually was on things like “roof vents,” which struck me as a bad target for thieves. I also didn’t know how I was going to get down from the roof once I managed to get there. That was a problem for later; that was a problem for someone who was already free, and that meant that it couldn’t be a problem for me. Until I was outside, I was still Sherman’s captive.

With no other way of marking time, I started counting off seconds in my head, chanting, “One Mississippi, two Mississippi,” as softly as I could. The minutes blurred into an infinite number of Mississippis, leaving me no more certain of how long I’d been climbing than I would have been without the count. At least the act of saying the numbers aloud made me feel like I was doing something, and kept me from focusing on the increasing weakness of my arms. I’d never done anything like this before. If my grip slipped even the slightest bit…

As if the thought had created the action, my sweat-soaked palms slipped on the slick tin walls of the vent, and I slid abruptly downward for what felt like a mile before I managed to jam my feet hard enough against the vent’s sides to stop my descent. My heart was hammering so hard that it felt like it was going to break clean out of my chest, and I could taste the bright copper penny burn of adrenaline on my tongue. What would have happened if I’d fallen all the way down to the bottom? It’s not like there was a pillow waiting there to soften my landing. I would have been lucky to get away with something as small as a broken ankle.

For one dizzying moment I hung there, suspended and afraid, and thought about climbing the rest of the way down before I could plummet. I would go back to the dressing room. I would crawl back through the grate before anyone noticed I was gone and came looking for me. I would go back to my bed and sleep off this headache, and when I woke up, I would be able to think of a better escape route. One that wasn’t so risky. One that didn’t carry so many consequences for failure.

You’re not going to do any of those things, I told myself quietly. There was nothing firm or stern about my little inner voice: if anything, I sounded despairing even to myself. I wasn’t going to go back, and I wasn’t going to come up with another escape plan, because there wasn’t another escape plan. It was this or nothing.

Knees shaking with the effort of keeping me suspended in place, I pulled one hand cautiously away from the wall and wiped my palm dry on my sweater. Placing my hand back against the wall, I repeated the process with the other hand. Then, taking a deep breath, I began to climb again.

If it had been hard before, it was pure torture now. I was dead tired, lactic acid was building up in my muscles, and falling was no longer an abstract “maybe”: it was a thing that had happened once and could easily happen again. I dug my nails into the grooves between panels of tin, climbing ever higher, trying not to think about what awaited me if I slipped. I’d managed to catch myself once. I wasn’t going to be so lucky a second time.

My right hand quested upward for the wall, and struck empty air. I trembled, forcing the rest of my limbs to remain rigid as I felt around, trying to find where the wall had gone. Finally, reaching down, I found the point where the vent curved. Hope surged through me, hot and red and burning. I was at the top. I had to be.

That, or the bend was going to lead me to a whole new tunnel system, and take me no closer to the exit. I pushed that thought aside. It was unproductive, and besides, I could feel the cool air flowing toward me. It was just a trickle, held back by whatever grating was on the front of the vent, but it meant that I was moving in the right direction, if nothing else.

With trembling hands, I pulled myself around until I was facing into the bend. There was still no light. Still, I hadn’t come this far to turn around at the first sign of trouble, and so I squirmed forward, working my way one inch at a time into the new leg of my journey.

The bend was barely the length of my body. Then it curved again, resuming its ascent—but the angle this time was more slope than sheer, and I was able to pull myself along without nearly as much fear of falling. My pulse was beginning to calm. There was something pleasantly familiar about moving through the dark this way, like it was part of what I had been made for. In a way, I suppose that was exactly the case. I was designed to live in dark, tight spaces, inside a human body. This was just life inside a building. Not that much difference, given the change in scale that I’d already undergone.