January has become a favorite month for studios to dump their leftover horror movies into, and the first to pop up this year is “The Forest.” The initial directorial effort by Jason Zada—who was one of the writers of the dismal 2014 found-footage flick “The Houses October Built”—is based on a promising premise but quickly devolves into a grab bag of routine “gotcha” moments embedded in a plot that slides into incoherence and torpor.

The story is set in motion when Sara (Natalie Dormer), a well-heeled westerner, experiences visions that her troubled twin sister Jess (also Dormer), who’s teaching at a school in Japan, is in trouble. When she’s informed that Jess has gone missing in Aokigahara Forest at the base of Mount Fuji, where people customarily go to commit suicide, she impulsively rushes there to search for her. Before plunging into the dense foliage—which, she’s warned, it’s particularly dangerous to enter sad—she meets Aiden (Taylor Kinney), a chatty, handsome travel journalist who arranges for them to accompany ranger Michi (Yukiyoshi Ozawa) on one of his walks through the forest to locate the bodies of those who have killed themselves. They stumble upon Jess’ tent and belongings—just one of the many happy coincidences in this huge place—and Sara insists on staying the night despite Michi’s warnings she should not. The intrepid Aiden refuses to leave her alone, and before long spookiness and apparitions proliferate, while Sara becomes suspicious of Aiden’s motives. An overwrought psychological element is added to the mix in terms of a traumatic experience the twins shared when they were six and witnessed their parents’ deaths. (Cue some badly-staged flashbacks.)

It’s possible that an eerily atmospheric thriller might have been fashioned from material dealing with the Aokigahara, but “The Forest” muffs it. It relies entirely too much on cheap shock moments—the first actually involves the hoary device of a scary person suddenly jumping into frame and slamming the window of a car, startling the person inside, and things don’t improve much thereafter (the second big jolt happens when a wizened old woman frightens Sara in the a similar way in her hotel). Once into the forest (actually located in Serbia for budgetary reasons, though there are some establishing shots filmed in Japan), the discovery of corpses is initially employed as the go-to mechanisms of inviting screams, until the so-called yurei—threatening ghosts—make their appearance. These look like ordinary folks dressed in raggedy garb with bags over their heads and cutting from one to another of them does not evoke the intended shudders. Nor does the deterioration of the relationship between Sara and Aiden engender much interest, since it’s never made clear whether her doubts about him are justified or just a manifestation of her own emotional problems. The conclusion is rather mystifying too—and not in a good way.

“The Forest” suffers from pedestrian work by Zada and cinematographer Matthias Troelstrup, which strands the two stars not so much in a dark wood as in a morass of tedium despite all the chintzy scare tactics. Though her accent slips from time to time, Dormer evinces a strong presence, even if the picture makes the dual role easier than it might have been by distinguishing the sisters by hair color. Kinney has an engaging, easygoing persona, but the script offers him little opportunity to use it to any great effect. Ozawa, the only other cast member given any appreciable screen time, acts convincingly perturbed.

“The Forest” isn’t bad enough to persuade you to consider entering the real Aokigagara yourself, but it will leave you sad over the thought of an opportunity missed. So you’d be well advised not to take the chance of venturing into this cinematic approximation of it either.