I climbed down twenty rungs before my feet touched concrete. The bunker was a large square room with smooth walls and a high ceiling. Fluorescent lights buzzed weakly overhead. Two boys—one of them the class monitor—ran to a panel with a lever and a red button. They pulled and pressed together. Somewhere above us, a fan whirred into life. Air rushed through vents in the walls, bringing the smell of wet earth and oil. A second set of fans near the floor began to spin, but they were different—large, bladed and loud, like the intakes on a jet engine.

A massive cylindrical container dominated the far side of the room. It was half the size of the bunker itself, made of stainless steel. Pipes and valves snaked into the ceiling. It looked disturbingly like a meat grinder.

The shaking above grew stronger. Dust cascaded down. A muffled crash echoed, then another. Screams filtered through the concrete. I pictured the walls collapsing, chairs splintering, children crushed. For a moment, I froze. The boys did not. They moved quickly but methodically, hugging each other, whispering words I couldn’t hear. Their faces were pale, eyes wide. Some clenched fists, others bit their lips. None of them cried. They had done this drill before.

My brain caught up. The teacher’s last instruction rang in my ears: green button, bookshelf. I scanned the room. In one corner, half hidden by a ventilation duct, stood a small shelf with a few binders and instruction manuals. Two buttons were mounted on its side—one green with a light bulb icon, the other green with no icon.

I hesitated only a second. I pressed the one with the light bulb first. The overhead lights brightened. Then I pressed the plain green button.

Something clicked within the wall. A section of concrete slid away, revealing a narrow passage with a staircase descending further into the earth. Small lamps lit the stairs with a soft glow. A draft blew up from below, carrying the faint scent of metal and ozone.

I turned to the boys. My voice came out surprisingly steady. “There’s a passage. Follow me.”

They didn’t argue. We lined up and started down the stairs. The metal rail was cold under my fingers. The sound of the fans faded behind us. My heart hammered in my ears. Every step took us deeper, away from the monsters above and into the unknown.