PARIS - Coming up with a new twist for a horror film without going down some very disgusting roads hasn't been that easy in the 21st Century.  It's one reason franchises like "Saw," "Paranormal Activity" and "The Purge" have hit such a cord with viewers and spawned a ton of sequels.  One film that's trying to add a new twist to the supernatural thriller (with more than a touch of horror thrown in) is the Dowdle brothers' "As Above/So Below" which arrives in theaters on Friday.

Originally, Relativity CEO Ryan Kavanaugh had an idea about staging a film in the catacombs of Paris, a labyrinth of tunnels and quarries beneath the streets of the city that stretch over 200 miles.  Shockingly, very few films had used the centuries old underground spaces as the setting for a movie.  Considering approximately 6 million human remains were buried (or re-buried) there it seemed like a creative opportunity if the right script came along.  Of course, it's worth noting the authorities had not granted many permits to even film legally down in the catacombs in the first place, but Kavanaugh convinced John and Drew Dowdle to try to fashion a movie about it. The brothers, who gained notoriety with "The Poughkeepsie Tapes" and "Quarantine," realized it would fit perfectly with a storyline they were working on that featured a female Indiana Jones-like heroine. And so became "As Above/So Below."

A year after production, on a sunny Parisian day in August, the Dowdles and stars Perdita Weeks (ITV's "Titanic" mini-series) and Ben Feldman ("Mad Men," the upcoming "A to Z") returned to the main section of catacombs where they shot a good chunk of "Below" to talk about the film.

Weeks plays Scarlett, an archeologist and explorer on the hunt for a mythical stone that is said to have transformative powers.  When a long lost clue leads her to the catacombs she recruits George (Feldman), an old friend living in Paris, to help her try and find it. And, as you'd expect, what they find may not want to be discovered. Moreover, they also find some truly evil things on their journey that may be more dangerous than that mysterious stone.  The Dowdle brothers intentionally leave many questions about this creatures or people (?) unanswered.

The 28-year-old actress was the first actor cast and that means she has more clues as to what is really going on "below" than the audience does.

"There were lots and lots of things that we discussed and there were several drafts of the film so I knew about a lot of the backstory," Weeks admits.  "It was all really fun to try and hint at all that stuff. And all the reveals that may or may not happen."

As for filming itself, Weeks admits that a few days had to be shot on a soundstage, but for the most part it was six weeks underground, every day.  And, to get to certain tunnels or quarries they went through obstacles you wouldn't expect on the set of a major motion picture.

"It was almost like a gully where you had to get on your hands and knees," Weeks says about one tough locale. "Everything dripping and the cameraman holding this incredibly heavy [piece of equipment]."

Feldman interjects noting, "I think the real horror was for the director of photography.  People keep asking us if we were scared, but I don't think we were. I'm sure he was the entire time."

An Emmy nominee for his work on "Mad Men," Feldman gives a tremendous amount of credit to the Dowdles for making it work conceptually and from a production standpoint.

"[They] had so much thought out and were really on top of this whole thing which was necessary because to shoot something down here and in the style we did," Feldman says. "The guerrilla kind of first person thing -- you really need to be able to trust the filmmaker because someone who is bad at what they do? That could have been a disaster. It could have been dangerous, ugly and stupid."

Weeks adds, "They had to be incredibly efficient with the style of shooting because especially with found footage you could have kept going and going and going. You have to be very regimented "We need to sop there.' 'We need to get this.'  After 12 hours or underground any crew would be, 'We've got to get out of here.'"

For more on Weeks and Feldman's thoughts on "As Above" from the actual catacombs where the movie was shot, check out the video embedded at the top of this post.

To hear more from the Dowdle brothers, click here.

"As Above/So Below" opens nationwide on Friday.

With over a decade of experience in the movie industry, Ellwood survived working for two major studios and has written for Variety, MSN and the LA Times. A co-founder of HitFix, Ellwood spends his time relaxing hitting 3’s on the basketball court and following his beloved Clippers.