Using the Aokigahara forest (aka The Suicide Forest, or Sea of Trees) near Mount Fuji in Japan, a real place where many people have actually committed suicide, as inspiration, The Forest spins a tale of twin sisters, Sara and Jess, both played by Natalie Dormer, who attempt to be reunited when Jess ends up missing, last seen conducting a school field trip in that forest where lost souls never return, at least not in living form. Sara travels 6,000 miles from America to go find her because, being her twin, she innately knows Jess isn't dead, even if everyone else seems to think there's no hope. Before she ventures into that dangerous forest, she meets and befriends a travel journalist who offers to accompany her, along with a Japanese guide named Michi, in exchange for interviewing her for the story. However, the forest is haunted by the yurei, ghosts of those who've perished before, whose sole purpose seems to be to get others to join them by preying on their despair.