The armored transports brought them to the edge of an old industrial rail yard on the city's periphery, completely hidden from the main grid. The rain slicked the rusted iron tracks as the group scrambled out, moving quickly toward a low-slung, reinforced concrete maintenance shack that looked abandoned to the naked eye.

Inside the shack, Woo-jin pulled away a heavy, rusted steel floor grating, revealing a narrow concrete shaft with a metal ladder descending into the dark.