“As Above, So Below ” opens on a bus entering Iran, where the film’s heroine, Scarlett (Perdita Weeks), explains to the audience that she has just entered the country illegally. With authorities already searching for her, she and an accomplice enter an underground ruin that, as Scarlett explains, the government plans to demolish very soon. She succeeds in locating her target, a legendary artifact called the Rose Key, which she has reason to believe will lead her to the fabled Philosopher’s Stone. As she records its inscriptions, the demolition commences. She narrowly escapes the collapse, but not before encountering a mysterious apparition of a figure from her past.

All this occurs before the film’s opening credits. The setup is intriguing and manages to engage the viewer well enough. In the following scenes, the film sets up a promising story and characters, and it boasts some solid atmosphere and suspense. However, after the first hour or so, “As Above, So Below” grows progressively more and more tedious until finally descending into downright silliness.

The film, which is presented as found footage, was directed by John Erick Dowdle, who has previously been involved in similarly styled horror movies like “The Poughkeepsie Tapes” in 2007, “Quarantine” in 2008 and “Devil” in 2010. With “As Above, So Below,” Dowdle at first seems to break free of cliche horror setups by drawing inspiration more from treasure-hunting adventure films like the “Indiana Jones” franchise or “National Treasure.” The freshness of this approach is commendable, but it is undermined by the multitude of other horror and fantasy cliches the film falls prey to as it runs its course.

After the fairly thrilling opening scene, the audience learns that Scarlett is continuing her late father’s work of searching for the Philosopher’s Stone, which, according to legend, grants its user extended life and mastery over matter. Travelling to Paris with her cameraman Benji (Edwin Hodge) on a hunch that the Stone is hidden in the catacombs beneath the city, Scarlett employs the help of vigilante clock repairman and ex-boyfriend George (Ben Feldman), and locals Papillon (François Civil), Souxie (Marion Lambert) and Zed (Ali Marhyar), all of whom have their own personal demons that come back to haunt them later in the movie.

The found footage aspect of “As Above, So Below” is itself enough of a cliche to put off many moviegoers right from the beginning, and this only makes it even more disappointing what little regard the movie seems to have for suspending disbelief. While the acting is convincing, there is occasionally a stilted line of dialogue, a suspiciously cinematic camera shot or an impossibly convenient turn of events that reminds the viewers that they are not, in fact, viewing a genuine account of an ill-fated expedition, but are actually watching a Hollywood production with a script and a multimillion-dollar budget.

Despite the lackluster storytelling, “As Above, So Below” does feature a few decent scares. After the group enters Paris’ notorious catacombs, home to the remains of more than 6 million dead, the movie adopts a disorienting and claustrophobic atmosphere, and for the most part manages to avoid cheap scare tactics. The characters soon lose their way in the catacombs, and tension begins escalating. To make matters worse, much of the scenery they encounter is disturbingly suggestive of traumatizing events from each character’s past. While this latter point is somewhat contrived, the film employs it with just enough subtlety and style that it is still frightening.

Another of the film’s strong points is how realistically the characters react to their situation. One particular scene, which finds Benji stuck in a narrow passage littered with bones and rats, does a very effective job depicting the character’s mounting dread and eventual panic, owing a great deal to Hodge’s performance.

Unfortunately, “As Above, So Below” peaks very early and grows tiresome from that point on. Its final scenes resort to flashy CGI effects to keep the audience entertained, but this only succeeds in making these scenes less scary and more ridiculous. Ultimately, the film shows potential in its impressive first half, but fails to live up to its impressive exposition.