A train pulls into the station with no driver at the controls and every seat empty - except for one. Mara Whitlock is the only witness on the platform when a stranger steps off and grips her arm, warning her to run before the whistle sounds again. What follows pulls her, reluctant detective Ethan Blackwell, and the enigmatic Daniel Cross into a decades-old mystery buried beneath the rail yard, where something rides the tracks long after the last scheduled departure. As the trio digs deeper, they learn the train was never meant to stop here at all, and that every person who hears its whistle a second time disappears by morning.