The summer movie season generally kicks off with a big, explosive event film, and Joss Whedon’s “The Avengers,” out today, is certainly that. For viewers looking for a quieter, more contemplative, but equally riveting alternative, they’ve found it in “Sound of My Voice,” an unsettling, engrossing story of a cult led by Maggie (co-writer Brit Marling).

Not everyone in Maggie’s cult truly believes in her. In fact, Peter (Christopher Denham) and Lorna (Nicole Vicius) have infiltrated her ranks with intentions of making a documentary about Maggie and her followers. However, Maggie has a certain way of getting into her subjects’ heads. As the film goes on, a chasm grows between Peter and Lorna as they struggle with their faith, their dedication and each other.

With a runtime of only 85 minutes, “Sound of My Voice” is almost abrupt in its brevity, setting up its concept quickly, letting us get to know just enough about the characters before challenging them and their beliefs, and then ripping the rug out from under the audience with its deliciously ambiguous finale. Director and co-writer Zal Batmanglij divides the film into 10 chapters, and there’s a definite sense of dread that builds until the film’s final installment. Batmanglij also finds the sinister in the seemingly harmless, be it in the white and beige basement where Maggie and her followers gather or a friendly hike through the woods between a few members.

Brit Marling hit Sundance last year with this film and last summer’s equally low-key sci-fi “Another Earth,” and “Sound of My Voice” is a better film in every way. As Maggie, Marling has an incredible, assured presence, and she paints Maggie not as a flawless deity but a hypnotic yet undeniably human figure. If Marling wasn’t so convincing in the role, “Sound of My Voice” would fall apart, but she manages to sell Maggie as engaging and magnetic, exactly the sort of person who would be able to amass followers easily.

Christopher Denham and Nicole Vicius both impress as the infiltrators of Maggie’s cult. Vicius’ Lorna has a past she’s not especially proud of, and it’s installed a skepticism in her that informs her character’s every move. Vicius gives a subtle, strong performance, but Denham’s role is much showier and his character is better defined. Denham gets to go toe-to-toe with Marling in more than one scene, and he never disappoints, making the audience just as confused and torn as he is. The film’s final moments, which are sure to be discussed at length in the coming months, make Denham’s Peter experience the unexplainable, and the wonder, fear and betrayal that cross Denham’s face in that moment lend the finale a gravity that makes it all the more gut-wrenching.

It would be easy for this film to get lost in the sea of blockbusters that will hit multiplexes in the coming months, but this is a really special one, a perfect example of accessible, low-key science fiction that makes great use of both its premise and its budget.

Whether Marling continues telling this story or another one entirely, her voice as a writer and actress is so strong and precise that the sound of it should be enough to inspire interest.

Printed on Friday, May 4, 2012 as: Summer film delves into cult culture