The concrete wall behind the warehouse was pockmarked with cracks, some spiderwebbing thin, others wide enough to fit a fist. I ran my fingers over one, the rough edges scraping my palm. It had rained last night, and the stone still smelled like damp earth, mixed with the faint stench of motor oil from the garage next door.
"Found it."
Chen's voice pulled me back. He was crouched a few feet away, squinting at a gap near the base of the wall. It was narrower than the others, almost hidden by a clump of overgrown weeds, but even from here, I could see the faint glow seeping through—pale, like moonlight through frosted glass.
I knelt beside him, brushing away the weeds. The gap was barely six inches wide, but when I pressed my ear to it, I heard something: a low hum, like a generator running far off, or maybe a voice too muffled to make out words.
"You think it goes through to the other side?" Chen asked, tapping the wall with his knuckle. The stone sounded hollow there.
I nodded, already fishing the crowbar from my backpack. "Last time we checked the blueprints, this section wasn't on any map. Must've been a rush job—they skimped on the rebar."
He grinned, the scar on his cheek crinkling. "Lucky for us, huh?"
It took ten minutes to wedge the crowbar into the crack and lever it open. Dust billowed out, making us cough, and when it settled, the gap was wide enough to crawl through. Chen went first, his boots scrabbling against the concrete as he vanished into the darkness. I followed, the beam of my flashlight cutting a swathe through the dark.
The space between the walls was tighter than I thought, barely two feet across. Cobwebs stuck to my arms, and I could feel the rough stone pressing on both sides, like the world was squeezing in.
"Careful," Chen called back. "There's a loose brick up ahead."
I tripped over it anyway, catching myself on the wall. My flashlight clattered, the beam spinning wild before settling on a corner—where something glinted.
"Hold up." I grabbed Chen's ankle, making him yelp. "Light."
He shone his flashlight over, and we both went quiet.
It was a metal box, rusted but still intact, wedged between two bricks. Carved into the lid was a symbol I recognized—a circle with three lines, the same one that was stamped on the old toolboxes from the factory fire five years back.
"You think—" Chen started, but I was already prying it open with the crowbar.
Inside was a stack of letters, yellowed but still legible, and a photo. I picked it up, my thumb brushing the edge. It was a group of people standing in front of the factory, smiling, squinting into the sun. I recognized Mr. Zhang, the foreman, and next to him was a younger Chen, missing the scar, and…
"Is that your dad?" Chen asked, pointing.
My throat felt tight. There he was, my dad, in his work uniform, arm slung over Mr. Zhang's shoulder. I'd forgotten he used to smile like that—bright, like he hadn't a worry in the world.
The first letter was dated 2015. "Xiao Lin, if you're reading this, the fire wasn't an accident. Watch the night shift crew—"
I stopped, looking at Chen. He was staring at the letters, his jaw tight. "My dad always said the night shift had 'bad eggs,'" he muttered. "Said they'd cut corners to meet quotas."
The beam of the flashlight shook in my hand. Outside, I could hear a siren, distant, probably the security patrol. We didn't have much time.
"Take the letters," I said, shoving them into my bag. "I'll grab the photo."
Chen nodded, already stuffing them into his jacket. We crawled back the way we came, the wall closing behind us as we levered the brick back into place. The sun was setting when we emerged, painting the sky pink, and I tucked the photo into my pocket, where it pressed against my chest, warm even through the fabric.
Chen clapped me on the back, grinning. "Told you this wall was worth checking out."
I smiled, but my mind was on the letter. Watch the night shift crew.
Whatever happened five years ago, we were one step closer to finding out. And for the first time in a long while, the dark didn't feel so heavy. It felt like a door, creaking open.