Brit Marling is on the verge of a breakthrough in her still-young career, and there's not a person around who can accuse her of succeeding by way of "getting lucky." Not about to wait around for someone to take a chance on her, she partnered with two aspiring director friends—Mike Cahill and Zal Batmanglij—and co-wrote and starred in a pair of eye-catching independent features that both made a splash at the Sundance Film Festival. 2011's "Another Earth" was a novel, thought-provoking sci-fi drama about redemption and individuality in the face of newfound knowledge that there is a planet identical to ours out there amongst the stars. "Sound of My Voice" is subjectively different but a companion in tone and genre, a contemplative look at the power of indoctrination and belief with fantastical underlying insinuations. Both are haunting. Both are provocative. Both overcome hints of pomposity and affectedness by proving to be so unique. Both end on a rapturous note that speaks volumes while barely needing to say anything out loud at all. And finally, both were clearly the result of the same major talent, Marling earning not one, but two, distribution deals with Fox Searchlight Pictures for her auspicious work. The key, now, will be to get the word out to the upscale public—you know, the type who didn't recently go rushing in droves to see "The Three Stooges."

Los Angeles-based substitute teacher Peter Aitken (Christopher Denham) and girlfriend Lorna Michaelson (Nicole Vicius) want to make a documentary together about cult groups, and what better way to do research, they figure, than to infiltrate one themselves. Under sketchy circumstances, they receive directions to a house in the Valley, are instructed to scrub down and change into plain white clothes, and then are blindfolded as they are taken via van to the actual location. Living in the basement of this mystery residence is the group's leader, Maggie (Brit Marling), a compelling question mark of a figure who claims to have traveled from the future—more specifically, the year 2054. Peter and Lorna are naturally skeptical, viewing Maggie as nothing more than a professional con artist, but there's also no denying the spell she seems to have on the others—and then, against their best judgment, on them. Could there possibly be more to what Maggie claims than just a total lie, or is Peter on the right track when he remarks that she needs to be stopped before she has all of them killed?

"Sound of My Voice" is menacing without director Zal Batmanglij needing to overtly pull strings, a quiet simmer of a thriller that could snap into a Jonestown-inspired horror show any second. Peter and Lorna come from very different backgrounds—his mom, a member of a New Age cult, died when he was thirteen, while she lived a privileged Hollywood life as the daughter of a hot-shot producer before breaking out—but they both know what it's like to get caught up in intoxicating counter-cultures with the power to destroy people before spitting them back out. In the enigmatic Maggie, they see someone whom they don't trust, but must pretend to. She's a riveting speaker and certainly plays the part by staying indoors, claiming that her immune system is weak and not used to the present day environment, but could she really, mystically, be from the future? It's a stretch, and so are the games she plays with her followers, instructing them to fast and then feed on worms in order to get used to the lack of food available a few decades from now.

Christopher Denham (2010's "Shutter Island") and Nicole Vicius (2005's "Last Days") serve their purpose as a point of entry into this abstruse underground group, what they are seeing the same as what the viewer is glimpsing for the first time. It's a strange, creepy, suspicious environment, but one that is notable for these traits and the authenticity it is lended by the makers. At the same time, there is something mildly distant about Denham's and Vicius' portrayals of Peter and Lorna, who either probably won't be together for long as a couple, or don't seem to click because the actors don't. This emotional disconnect nonetheless works in the long run, if only for the suggestion that what Maggie's circle provides might be what one or both of them is unconsciously searching for.

Tantalizingly played by Brit Marling, Maggie is a hypnotic force, the kind of person you stop and pay attention to when she enters the room. Just when it seems as if her stories of coming from the future are unraveling in logic, there seem to be explanations that point in a different direction. In one superb scene, Maggie is asked to sing a song from the future. She chooses 1990s hit "Dreams" by The Cranberries, and the rest of the group recognizes it. Her explanation for this anomaly is surprisingly logical, as if her similarly convincing argument for not being able to name a significant event that occurred twenty years before she was born. By always keeping one questioning her validity, a lingering uneasiness persists. If she is from the future, what are the implications of this? If she's not, what else is she capable of doing or lying about? A fraud or not, Maggie—and Marling—are enthralling originals.

Against his better judgment and the warnings of Justice Department worker Carol Briggs (Davenia McFadden), Peter agrees to do Maggie a favor at the expense of breaking the law and potentially getting into trouble. Hoping to steal the upper hand, though, he lures her from her comfort zone and to the Museum at the La Brea Tar Pits for an encounter that could either cement her claims or prove her deceit. The ending of "Sound of My Voice" provides an answer even as the scope of ambiguity—the hows and the whys—grow all the more. Opening up a whole new boatload of questions just as the story comes to its most natural and honest and critical of conclusions, the film at once expands the horizons of its characters' lives and environments within the universe while giving Peter and Lorna a purpose to continue questioning that which they do not know or understand. How do any of us hope to learn, after all, if we do not embrace our ability to doubt? Though perhaps too claustrophobic for its own good, "Sound of My Voice" is the work of visionaries, excitingly about much more than just a fishy cult and smart enough to allow each viewer to take away from it what they personally choose to.