In January of 2022, a solo traveler named Cassie pulled off Interstate 90 near the small town of Winton, Montana, after her Subaru's check-engine light came on. She expected a quick stop at a gas station, maybe a mechanic in the morning. What she found was a stretch of road that didn't match any map, a gas station attendant who warned her not to listen for the horn, and a sound that turned her certainty inside out. This is the story Cassie told me last summer, sitting in my kitchen with her hands wrapped around a mug of cold coffee. She still drives, but she never takes I-90 west of Bozeman after dark. And she still hears the horn sometimes, even when the engine is off. Luna recounts a quiet, creeping encounter with something that lives on a dead mile of highway — not a monster, not a ghost, but a warning she wishes she'd heeded.