Plot
In a flash-forward, a figure grabs a camera and walks through a murky corridor with audible human screams. The figure puts the camera in a disposal chute, which opens into space in Earth orbit, and the camera falls to Earth. Information on-screen then reveals the footage about to be screened is being used as part of Project Blue Book, regarding an incident in 2011 where 27 people vanished near Brown Mountain, North Carolina.
Riley Morris, an autistic boy, keeps a video journal while on a family camping trip to Brown Mountain with his father Peter, his mother Katie, and his siblings Corey and Jillian. On the last night of their trip, Riley is startled by flashes of light outside of the tent. The children see lights in the sky that promptly vanish.
Driving home the next morning, the family are sidetracked when their GPS mysteriously misdirects them to an isolated route. They lose their cellphone signals and the car runs low on gas. A crow unexpectedly falls beside the car, dead.
The family reach a tunnel that is blocked by recently-abandoned vehicles. Peter, Corey and Riley leave their car to investigate, while Katie stays behind with Jillian. Personal belongings are scattered around some of the cars, and it appears the missing occupants were forcefully removed from their vehicles. Peter sees a humanoid silhouette at the end of the tunnel and calls out. Upon realizing the approaching figure is not human, he tells the boys to run. He is engulfed in light and convulses before disappearing.
The boys reunite with Katie and Jillian. As they try to drive away, a murder of crows falls on their car, which shuts down. They hear a blaring sound and flee to a cabin they passed earlier. The cabin's owner, Sean, is a rustic recluse who is initially hostile towards the family, but changes his mind when he hears his guard dog being attacked by something that followed them from the tunnel. Sean and the family barricade themselves inside his house for the evening. Sean explains that the Brown Mountain Lights and mysterious abductions have been a local recurrence for centuries. Upon hearing a radio message from his brother Scott, Sean leaves to look for him.
The cabin is eventually breached and in an effort to save his family, Corey hides the others in the cellar, blocking the door, before alien beings enter and abduct him. The remaining members of the family are saved by Sean, who explains that Scott was also abducted and takes them to his truck, planning to drive them back to town down the mountain. The aliens find the group, and Sean tells the others to head to a nearby barn and take refuge. Sean catches up with them, and the group attempt to leave the barn, but the aliens return and Katie and Sean are abducted. Riley and Jillian take refuge deep in the woods for the night, hiding from the aliens.
Climbing down the mountain at dawn, Riley and Jillian see a town in the valley below and soon find a road, but their hopes are dashed when it leads back to the tunnel where Peter was abducted. A police car arrives, but the aliens return and abduct the policeman, Jillian, and Riley, who is still clinging to the camera. The remaining footage shows a rapid ascension into orbit, before cutting to the footage from the beginning of the film. After the camera falls back to Earth, two men in respirators and Hazmat suits are seen taking it away in a U.S. Air Force van.
In a mid-credits scene, one year later, a North Carolina state trooper finds Peter huddled on a bridge, naked, disheveled, and in a state of shock. The fate of the rest of the family is uncertain, but comments made by the police officer on his radio suggest that Peter is not the only member of the family to have been found.
