Dating back to the 18th century, the Catacombes de Paris have housed the skeletal remains of nearly six million bodies, their resting place relocated from the condemned Holy Innocents' Cemetery to the underground ossuaries. It goes without saying that it is a prime location to set a horror movie, but it is made all the more novel for having never before been used as a feature film's central locale. That writer-director John Erick Dowdle (2010's "Devil") and co-writer Drew Dowdle (2008's "Quarantine") were permitted by the French government to shoot down there is a major get in and of itself, but even more amazing is the allowance they received to voyage to heretofore illegal areas off-limits to the general public. While "As Above, So Below" is yet another entry in the shaky-cammed found-footage arena, the style generally works here and stays mostly true to its aesthetic. With only one notable exception where a too-apparent edit occurs, sacrificing the honesty of its first-person conceit in the name of getting a scare, the picture steers clear of cheating its audience or manipulating them with the use of a superfluous music score. The dank, despairing authenticity of the catacombs proves exceptionally effective, made all the better by a hair-raising premise that twists expectations while fearlessly confronting common human struggles involving sorrow and regret.

A university professor specializing in archaeology and symbology, Scarlett Marlowe (Perdita Weeks) has taken after her beloved late father by traveling the globe in search of undiscovered places, objects and scripture. Her latest target is the subterranean lair existing beneath the streets of Paris, a place where she is convinced a secret passageway exists housing the legendary philosophers' stone. Enlisting the help of faithful documentarian Benji (Edwin Hodge), reluctant former colleague George (Ben Feldman), and knowledgable guide Papillon (François Civil)—whose girlfriend, Souxie (Marion Lambert), and best friend, Zed (Ali Marhyar), tag along—Scarlett & Co. begin their downward climb. The further they descend, the more they dare to uncover that hasn't been glimpsed for hundreds of years. When the path behind them becomes blocked, however, they have no choice but to cross a threshold where their escape—and survival—are no longer certain.

In terms of the sheer claustrophobia seeping from its every pore, "As Above, So Below" reminds favorably of 2006's terrifying cave-diving thriller "The Descent." Its story, though, is thankfully no copycat, going in a direction that endeavors to become something different from a traditional creature feature. The characters, save for the intrepid, foolishly brave Scarlett, are functional participants more than three-dimensional personalities. They are prone to some head-scratching reactions—none of them, for example, seem to be all that fazed when a strange man (Cosme Castro) who disappeared two years prior suddenly shows up in the tunnels, nor do they bother discussing the ghostly little boy they pass right by—but eventually recognize the gravity of the situation once they are faced with a casualty among them. A panic attack Benji experiences when he gets trapped in a tight space mounts in intensity with every one of Edwin Hodge's (2014's "The Purge: Anarchy") hyperventilating gasps, while the discovery of a preserved corpse on a slab elicits a jittery apprehension.

With every corridor they venture through, every obscure corner they turn down, every pile of bones they crawl across, every hole they lower into and every crumbling wall they penetrate, Scarlett and her cohorts flirt perilously with disaster. By the time they come upon a shaft bearing an inscription ("Abandon all hope, ye who enter here") signaling no less than the entrance to the gates of Hell, they have gone too far to turn back—and couldn't anyway, thanks to a boulder collapse. As reality splinters, hallucinations plague them and ancient unholy terrors pounce, the film turns into an increasingly surreal, provocatively ambitious fright show with a seat-jolting smorgasbord of seriously chilling moments. The second half of "As Above, So Below" is abstract in a way that laughs in the face of the laws of gravity and physics while emulating the daydream logic of a horror-loving child with an overactive imagination. Testing the audience's suspension of disbelief while simultaneously strapping them down for what amounts to an unnerving dark ride gone vicious, the picture takes chances and works because of its tireless ambition.

"As Above, So Below" is graced with an absorbing deliberateness, drawing the viewer into its suffocating, one-of-a-kind surroundings before unleashing a grab-bag of shivery payoffs. There is a welcome European sensibility at work, one that takes its time, embraces the offbeat Grand Guignol, doesn't concern itself with neat explanations, and still finds time to slip in streaks of interpersonal melodrama. Scarlett has spent much of her adult life defending her adventurous passions and denying the comparisons to her father, an explorer whose mental breakdown led to his own suicide. Her guilt—and that of George, whose little brother drowned in a cave when they were younger—will manifest itself as their fates are decided, the tragedies from their pasts intertwining with an unearthly realm from beyond. "As Above, So Below" is fraught with potent imagery, from a ringing telephone where none should exist, to a dusty piano, to a cryptic car ablaze hundreds of feet below the city's surface. Delivering a more riveting journey than ultimate destination, the film excels as a fantastical, thick-tensioned mood piece with an eye for the deliciously, preternaturally unknown. It also happens to be damn scary.