A frustratingly not-terrible action thriller.
For a while, "The Forest" defies expectations. We're used to the usual scare sequences, in which some eerie music plays on the soundtrack while some character wanders through a spooky locale. The music builds as the inevitable startle moment approaches, and when it arrives, there's the dissonant, deafening sting to accompany the howl/screech/yell of the frightener and whatever terrifying form it takes (monster, masked killer, pale demonic child, etc.).
In his debut feature, director Jason Zada doesn't quite take the usual route. Sure, our protagonist wanders through an assortment of dark, potentially haunted places, but that score is absent. There's a reliance on building tension with editing rhythms and ambient noise here that theoretically is refreshing. When the inevitable does arrive, that jarring music cue is absent (the growl/shriek/scream is, of course, still present, because the audience's reflexes have to be tested somehow). Zada clearly knows that the usual tactics have grown stale and predictable, and while he isn't exactly reinventing the wheel here, he's at least reducing some of the traction by eliminating an aural redundancy.
It doesn't last for the entirety of the movie, though. That would be hoping for too much at a time when it seems that every other (if not every) mainstream horror movie feels obligated to end with a shot of the visage of some allegedly frightening entity rapidly approaching the camera. This movie does not buck that trend, and indeed, the other cheap, familiar tactics eventually show up here, too. In the meantime, there are plenty of other ones to compensate for the ones that are absent but not missed.
The story follows Sara Price (Natalie Dormer), who has come to Tokyo after receiving a call from local police that her twin sister Jess (also played by Dormer) has gone missing (it's a little amusing that Sara shows people a picture of Jess when all she really needs to do is point at her own face and say, "But she has black hair"). Jess was last seen walking into Aokigahara, a forest at the base of Mount Fuji that has become known as the "Suicide Forest," on account of the considerable number of people who end their lives within it. Legend is that spirits in the forest feed on people's sadness, driving them to suicide. The sisters, of course, have a traumatic event from their past that is easy fodder for the spirits.