It was a Tuesday in late October, just past midnight, when the freight train jumped the tracks outside of Meridian, Mississippi. Luna's uncle was the first responder on scene — a volunteer firefighter who'd seen plenty of wrecks, but nothing that left the air smelling like wet copper and old roses. The train had been carrying something in a sealed tanker car, something that hadn't been on the manifest. By the time the investigators arrived, the car was empty. But the sound didn't stop. A low, rhythmic thrum, like a heartbeat underground, that kept playing back through the town's storm drains. Luna's uncle started hearing it in his sleep. Then the calls started coming in — people finding wet footprints on their porches, leading nowhere, fading at the door. This is a story about what happens when a town hears a train that never arrived, and the thing that walked away from the wreck without a sound. It stays with you, that night. It stays in the ground. And sometimes, when the wind is right, it hums back.