Sara (Natalie Dormer) wakes up suddenly from a nightmare and knows instinctively that something is wrong with her twin sister Jess (also Dormer). She is in the United States while her sibling is in Japan, working as a schoolteacher, but she isn't answering her phone and Sara has no way of contacting her, so the only solution she sees is to pack her bags and head east to the Land of the Rising Sun. Her boyfriend Rob (Eoin Macken) tries to persuade her not to worry and that Jess is fine, but she finds that hard to believe; thanks to a sixth sense about her, Sara knows she is still alive, but also that she is in trouble. When she lands in Tokyo, she has difficulty finding her bearings, not speaking the language, but she is not going to let that stop her...
The Forest was yet another white, Western tourist in danger in a foreign place movie, and for that reason as such premises came under greater scrutiny come the twenty-first century, proved controversial when the reaction was none too benevolent. But more than that, its critics believed it was making light of a notorious suicide spot in Japan, the Aokigahara Forest, and citizens killing themselves was seen as a particularly bad problem in that country; imagine a Japanese crew making a horror movie about the poor souls who throw themselves off Beachy Head or The Golden Gate Bridge every year and you'll have some idea of why this was regarded as being in extremely bad taste.
That said, there had already been horror movies actually made with the involvement of Japanese filmmakers about the forest in question, so perhaps it was more a case of what was culturally acceptable when those closer to the tragedies were able to invent stories about the subject and those seen as outsiders were more off limits. And it wasn't true to say that director Jason Zada and his team were having a laugh with the concept, as they took it very seriously, it was simply the way they approached it that you could very easily have an issue with. This wasn't Lost in Translation with vengeful ghosts, it was sincere in its concerns that visiting the location could encourage you to end your life, yet how it went about it was more of a drawback.
For a start, Sara as written was a rather testy character, you kept expecting her to lose her temper with everyone when she couldn't quite grasp what the Japanese folks were saying to her, which made her difficult to warm to. As she inexorably makes her way to the forest of the title through the city, she acts as a detective investigating her sister's disappearance, which even at the close of the story we are little the wiser as to why she vanished; she seems to have had psychological troubles stemming from a childhood trauma that Sara sort of shared, though even that is kept out of the reasons why any of this is happening. Keeping the audience in the dark was all very well, but this more than risked superficiality, it crossed the line into falling back on current horror movie tropes that were not helpful.
So you had the fear of self-destruction, creepy rural scenery (not actually filmed in Japan, they used an Eastern European stand-in), weird kids, a potential serial killer, and so on, cliché upon cliché which did not assist the production in its tackling of the severe themes it brought up then proceeded to do nothing with. The sense of very little of this being thought through aside from where the next jump scare was coming from was palpable, and did the filmmakers no favours, so you found yourself giving up on any of that and resorting to wondering why Sara cannot bring herself to trust anyone, and why the script would have it that she is justified in that approach for too much of the time. Most of the narrative took place out in the trees, once again invoking The Blair Witch Project, which was a fiction some believed to be true rather than a truth made into a fiction as The Forest was; it just didn't justify itself when it failed to do very much that was effective with its ideas, leaving the talented Dormer stuck in reaction mode and everyone else, including Taylor Kinney as the journalist who wants to assist, a possible threat. Not something that made you give up the will to live, but maybe think twice about watching fright flicks that don't think important things through. Music by Bear McCreary.