In the fictional mining town of Bethelwood, Maine, a young girl named Sally Kauffman searches for her missing cousin Emily, papering the streets with posters in the hope of finding her. After a run-in with school bullies leaves her stranded, Sally boards a cable car and is pulled into a nightmarish parallel world crawling with monsters that echo her own fears. Armed with little more than a flashlight, she must sneak and survive through this dark reflection of her town, guided by a mysterious old man named Charon, as she tries to rescue Emily and confront the painful truths of their past.