Movies that frighten on a really primal level, their gut-wrenching effect lingering long after the end credits have rolled, usually only come around once every few years. It is one thing to make an audience jump from their seats in the moment, but quite another to build such a pall of uneasy dread and apprehension that the characters and the unimaginable—yet somehow highly imaginable—situation they are in take on a lingering life beyond the screen. This is certainly what happens in "In Fear," a minimalist genre suspenser from writer-director Jeremy Lovering that takes the simple premise of two people lost on the back roads of the Emerald Isle and turns it into a conduit for pure, mounting terror. Showing beautiful restraint and very little violence or bloodshed, Lovering trusts in himself and the assured abilities of his actors and crew to keep the antsy, on-edge momentum constantly rising to alarming new heights. By additionally concentrating on the psychology concerning people dangling upon the vulnerable edge between life and death, the filmmaker takes the time to simultaneously explore fear as an emotional state of mind and physical manifestation. Normal, perfectly sane human beings are capable of much more than they think when placed in extreme circumstances where survival is no longer a certainty.

Tom (Iain De Caestecker) and Lucy (Alice Englert) have only been going out for two weeks when he invites her to a weekend festival in Ireland. His surprise to her before the event is a night's stay at the supposedly romantic Kilaidney House Hotel. Getting there, however, will not be quite so easy. As the roads narrow and the woods deepen, Tom and Lucy find that the signs to the inn are leading them in circles. As night falls and frustration sets in, baffling occurrences lead Lucy to suspect that someone is following them and toying with their sense of dislocation. With the car's fuel dwindling, their limited window of time to escape their pursuer and the isolated maze around them lessens. Soon enough, they'll be out of options.

From roughly the five-minute mark to the final shot approximately 80 minutes later, "In Fear" unnerves in its depiction of encroaching disquietude leading to sheer panic. As Tom and Lucy follow a rustic hotel van that is supposed to be leading them from a pub where they had briefly stopped to their general destination, already the mood feels off-center as the vehicle zooms down the scenic artery just a few paces too quickly. Once it heads in a different direction and the young sort-of couple pass through the entrance gates of the road to the Kilaidney House, they are not yet privy to the knowledge that there will be no turning back. The further they press on, the more hopelessly lost they get. While rustling around in the backseat during a brief stop, Lucy thinks she feels something or someone behind her taking gentle hold of a strand of her hair. Moments later, the car alarm starts blaring and they find the keys tossed in the dirt nearby. Are supernatural forces at work? Is the guy from the pub with whom Tom got into a brief confrontation messing with them? Is there a psychotic local lurking about who is tracking their every move? One of the spooky pleasures of the picture is in following these two protagonists with no foreknowledge of what is going on. What they experience, the viewer experiences with them—sometimes while clenching the armrest and/or peeking through fingers.

Alice Englert (2013's "Beautiful Creatures") and Iain De Caestecker carry the story, delving into intimidatingly dark internal spaces while acting as the minds and ears of the audience. Their Lucy and Tom are not extensively developed, what is revealed about them only the little they know about each other. What is most definitely identifiable about them are the cavalcade of feelings they must process and go through while being persistently scared out of their minds. It's a gripping yet necessary conceit, ratcheted all the more once the puzzle pieces of their living nightmare begin to sort themselves out. Saying more than this about where the story frenziedly leads would be too much, and director Jeremy Lovering earns the right to keep the turns in his narrative shielded from premature view. That he gave his performers the basic idea of what they should do in each scene without handing them a written script adds to the nerve-jangling reality with which Englert and De Caestecker bring to their roles. And, if Tom, like so many men in horror movies, takes longer than one would like to believe Lucy's claims of someone stalking them, he comes around soon enough—and then some.

"In Fear" stings and chokes in a blanket of trembling claustrophobia, the masterful lensing by cinematographer David Katznelson encapsulated in haunting shots where the gnarled, barren branches of the forest's trees take on the appearance of claws closing upon Tom and Lucy's car. Katznelson's framing of Lovering's threateningly lonesome settings is of the highest caliber, while scenes involving a scarecrow, a mysterious house, a rainstorm, and Lucy laying witness to something horrifying that Tom has his back turned from are enough to elicit involuntary gasps and screams. A flurry of mood-drenched sound effects and the layered, almost industrialized music score by Daniel Pemberton (2013's "The Counselor") and Roly Porter keep tensions at a lofty clip. Perhaps the most chilling moments, though, are the ones where the automobile moves onward down pitch-black country paths, the people inside stranded without an exit as their gas gauge perilously points toward empty and their headlights threaten to reveal something unthinkable at any time. "In Fear" is an experiment in precisely what its title describes, but there is a canny fluidity to its direction and uncompromising sensitivity in how its characters react and deal with their fates that lift it above being just an effective device for jack-in-the-box-style jolts.