A gripping, low-fi, arthouse mystery/thriller that steadily swells the pulse of viewers, like an incrementally inclined treadmill, Sound of My Voice is a joint exercise in disquiet and intellectual provocation, and far and away one of the best cinematic offerings of the year so far. Slim but still never less than spellbinding, the low-budget feature serves as a lesson in the power of storycraft, and further confirms the talents of burgeoning multi-hyphenate Brit Marling.

Skipping past any of their recruitment or plotting, the Los Angeles-set Sound of My Voice delves into the story of a pair of would-be indie documentarians — Peter (Christopher Denham, above left), a substitute teacher, and his girlfriend Lorna (Nicole Vicius), a reformed party girl — and their infiltration of a cult. Their plan is to expose as a sham and con artist its leader, Maggie (Marling, above right), a frail and softly spoken twentysomething woman who sports a tattoo on her ankle that she says marks her from the future, and the year 2054. Supposedly allergic to the toxicity of the modern outdoors, Maggie lives in guarded seclusion in a basement in the San Fernando Valley, where she relies on organic, homegrown vegetables and occasional blood transfusions from her adherents for survival.

Peter and Lorna come and go several times, showering and donning white robes with each visit. Maggie doesn’t so much preach doom-and-gloom as just subject her impressionable charges to a number of group mental exercises. After witnessing Maggie seemingly break Peter down, though, Lorna begins to question the sincerity of his adamancy that he still believes Maggie to be a fraud; the energy behind their documentary project seems to wane. Things finally come to a head, and turn possibly dangerous, when Maggie asks Peter to bring a specific young girl, Abigail (Avery Pohl), from his class to her house.

Like Marling’s other big break-out movie from last year’s Sundance Film Festival, Another Earth, Sound of My Voice is born of a unique screenwriting collaboration between Marling and its director, in this case Zal Batmanglij. The project originally had its roots as a planned web series — hence the 10 untitled chapters in which the movie unfolds, most of which are capped with nice little revelations or moments of emotional suspense. Far from giving Sound of My Voice a choppy, episodic feel, however, this tack helps feed a well-groomed atmospheric tension, and immediately deflate any misguided notion that the film is going to go off the rails into muscle-bound or derivative thriller territory.

Yes, like last year’s stirring Martha Marcy May Marlene, Sound of My Voice also focuses on a cult. But there are other (positive) similarities to that film too, like an emphasis on psychologically telling long-form scenes, and in the manner in which they each indulge in slow revelation. Marling’s performance is a beguiling mix of Earth Mother playfulness and emotional remove that never tips over into the reservoir of menace one might expect. Instead, via a sly and masterful juxtaposition of Maggie’s physically stricken vulnerability, quiet manipulation and pinprick hectoring, Marling and Batmanglij craft a character who, perhaps somewhat improbably, is even more interesting, reveling as she is in playing a role. Denham, too, gives a masterful turn, and stands on the cusp of breakthrough recognition; after having toplined the underappreciated Cinequest offering Forgetting the Girl, he’s already completed production on Ben Affleck’s latest directorial effort, Argo.

Years from now, Sound of My Voice will still effect the same emotional hold and connection, but have some additional value as one of the little, curious filmography entries in a couple notable careers. In the present day, however, it’s no less special — a delicate, mesmeric thing that dances darkly along the edges of psychology, religion and science-fiction, raising questions about faith, identity, self-betterment, epistemic closure and romantic connection. For the full, original review, from ShockYa, click here. (Fox Searchlight, R, 84 mintutes)