Black Mountain National Park has long harbored a strange history, from masses of missing livestock that have wandered onto the mountain to unusual disappearances and reappearances of local townspeople. One such case involved members of the entire Wahldrov family, who were never found. Cassian Wahldrov returns home, to the town of Black Mountain, following the disappearance of his autistic younger brother Manny. Together, he and his sister Mae set out to find their lost brother. Their efforts are quickly overshadowed by a strange force that both splits them up and slowly picks them apart.