In the small town of Lillian, Ohio, in 1979, a group of young friends sets out to film a zombie movie with a Super 8 camera for a local film competition. While shooting a scene at a deserted train station, they witness a catastrophic train crash, barely escaping with their lives. Among them is Joe Lamb, a boy grieving the recent death of his mother, who forms a deepening friendship with Alice Dainard, a girl from school who agrees to act in their amateur film. The crash seems peculiar to the children, as they soon discover that it was no accident; an enigmatic presence was being transported by the train, and the crash has now apparently freed it into their town.

Following the incident, strange occurrences and inexplicable events begin to unfold in Lillian. Dogs run away, machinery and electronics go missing, and the local sheriff vanishes mysteriously. The military arrives, led by a shadowy figure, and overtakes the town under the guise of cleaning up the train wreckage. As the children continue to piece together their movie, they inadvertently capture clues about the peculiar happenings on their film. Tension rises in the community as secrets are kept, and the truth about the train crash seems intertwined with occurrences that challenge the reality the town's residents have come to know. The kids' curiosity propels them deeper into the mystery, unwittingly drawing them closer to an extraordinary discovery that will change their lives forever.