What horrors lurk beneath the streets of Paris? All you could imagine and more in “As Above, So Below,” a Gallic-accented American thriller that throws everything but the devil’s kitchen sink at six attractive young spelunkers.

Purportedly shot by its characters’ head-mounted mini-cams, the movie is another example of the found-footage genre, although it doesn’t bother to explain how the raw video came to be edited into the finished product. Most of the action takes place in deep shadows or complete darkness and amid booming, howling noises, all of which attempt to cover for the frequently incoherent story. But writer-director John Erick Dowdle and his brother and co-writer, Drew Dowdle, include enough clever touches to prevent the movie from becoming just another “Paranormal Archaeology.”

The story begins in Iran, where Lara Croft-y Scarlett (Welsh television actress Perdita Weeks) is taking huge risks in search of something or other. The shakycam is even wobblier here than in subsequent scenes, so the sequence is indecipherable. But she later tells American ex-boyfriend George (“Mad Men’s” Ben Feldman) that she found a key that will lead to the Philosopher’s Stone.

As Scarlett explains to documentary maker Benji (Edwin Hodge), she knows multiple languages and has several PhDs, including one in symbology. That’s the specialty of Robert Langdon, hero of the “The Da Vinci Code,” the plot of which seems almost plausible compared to “As Above.” It turns out that Scarlett really believes in the Philosopher’s Stone, which allegedly turns lead into gold, among other magic tricks.

Convinced that this treasure lies in the catacombs under Paris, Scarlett rushes to George, who can translate Aramaic. (What does Aramaic have to do with alchemy? Hard to say, but the Dowdles seem to think all dead languages are interchangeably mystical and cool.) Although he’s understandably wary of the headstrong Scarlett, George ends up joining her and Benji on their underground expedition.

Explorers search for the Philosopher’s Stone in the catacombs beneath Paris in the found-footage horror film “As Above/So Below.” (Universal Pictures)

Their native guides are tunnel rat and graffiti tagger Papillon (François Civil) and his two pals (Marion Lambert and Ali Marhyar). You can’t make a horror movie without a couple of dispensable characters.

The remains of some 6 million people rest in the catacombs, which makes them plenty creepy. And the Dowdles, whose 2010 film “Devil” was set almost entirely in an elevator, know how to make even the least claustrophobic viewer feel the clammy terrors of confinement. They also end the movie with an amusingly playful touch.

But the filmmakers, like their heroine, can’t leave well enough alone. So they splash some Freud into their mishmash of alchemy, Egyptology, Satanism and Dante. In addition to supernatural evil, the main characters must confront their own guilt about catastrophic past failings. It’s all too much. “As Above, So Below” is inherently absurd, but it would be somewhat less so had it fully committed to just one of its ridiculous premises.

½

R. At area theaters. Contains bloody violence, profanity and partial nudity. 93 minutes.