SATURDAY 12:23 A.M.

Because of the drifts of snow on top of a dumpster, I managed to reach the lowest sill for a second-floor opening. It might have been a large window, or a delivery bay, although why it would be on the second floor, I had no idea. Or maybe it was an egress for finished product into railroad cars that used to pull up to the building.

I scrambled up. The old wood that had been used to board up this entrance hadn’t been replaced. The first floor was a fortress. Up above, not so much. The worst moment was when I slipped on the ledge and almost fell head first back into the alley. With all the noise from the emergency vehicles and the wind howling around the building, any noise I made on the outside was covered.

In the car on the way here, I’d studied the plans Duncan had found and sent to our phones. This side of the building was most likely to be still unused, as the offices were on the far side. This side used to have huge furnaces. I was on the south side of the building, about a quarter of the way toward the east side of the structure.

When I got inside, I let my eyes adjust to the far dim lights from a few exit signs that still glowed at wide intervals. The few openings that let in light from outside weren’t close enough or large enough for me to get a notion of what was happening.

I was at an intersection of narrow metal, lattice-work walkways. I replaced the boards I’d moved. As far as I could see, this part of the building was still abandoned. It didn’t feel like it was heated, but then it wasn’t out in the howling wind and the below-zero weather either.

The four-foot-wide cantilevered walkway I was on followed the wall both to my left and right and straight ahead of me. The parts against the brick wall were attached to it with industrial-size rivets.

All the metal had a thick covering of dust. Maybe no one had been on this since the place shut down.

The interior was an Escher-like effect of ramps and walkways and stairs that mostly hugged the walls, but some of them leapt out over the vast silence below. The top ramps and stairs soared into the dimness perhaps to the ceiling.

The cauldrons of the blast furnaces reminded me of the old videos they showed us in high school of manufacturing in America. Silent now as the furnaces in the Lonely Mountain in The Hobbit movie before Smaug blasted them to life.

A door banged open below me far on the right. It slammed shut seconds later. In the brief interval that it was open, I could hear the sounds of emergency vehicles.

I tried taking a step to my left. The walkway groaned. I tried to the right. Even more noise. I tried forward away from the walls and out over the floor far below. Much less noise, certainly far less than the other two choices.

I got to my hands and knees. I figured four points of touching with less weight on each rather than two feet were better. After being as certain as I could that I hadn’t been discovered, I began to crawl out over the dimness.

With each movement I tried, the thing shook more than I liked. As if it, with me on it, was in the middle of an earthquake.

Was there an alarm system? I hadn’t seen one, but modern ones can be sophisticated. Too late now.