Sound of My Voice is a 2011 American psychological thriller film directed by Zal Batmanglij in his feature directorial debut. The screenplay was written by Batmanglij and Brit Marling, and the film stars Christopher Denham, Nicole Vicius, and Marling. The plot focuses on two documentary filmmakers who infiltrate a cult led by a charismatic woman who claims to be from the future.

The film premiered at the 2011 Sundance Film Festival and was also selected to close the 2011 SXSW Film Festival. It was released by Fox Searchlight Pictures on April 27, 2012.

In Los Angeles, substitute teacher Peter Aitken and his girlfriend, aspiring writer Lorna Michaelson, are making a documentary about a secretive cult. Their goal is to expose its leader, a mysterious woman named Maggie, as a fraud.

After being deemed ready, Peter and Lorna are instructed to shower thoroughly and dress in white surgical gowns. They are then driven blindfolded to a secret basement location. There, they are received by Klaus, with whom they perform an intricate, practiced handshake. Inside, they join eight other members to meet Maggie, who uses an oxygen tank. She explains that the strict hygiene protocols are necessary to protect her from her severe illness.

Maggie claims she is a time-traveler from the year 2054. She describes a future of war and famine and says she has returned to select a group to prepare for the coming hardships. Maggie leads the group through intense psychological exercises, but she never definitively proves or disproves her extraordinary story. Her charisma is powerful, and both Peter and Lorna find their skepticism wavering. Lorna grows concerned as Peter, who was initially the most adamant about exposing Maggie, seems to be falling under her spell.

After several meetings, Maggie instructs Peter to bring her Abigail Pritchett, an eccentric eight-year-old from his class. Maggie claims the girl is her mother and threatens to ban Peter and Lorna from the group if he fails to comply. When Peter considers following Maggie's order, Lorna is outraged. Soon after, Lorna is privately approached by a woman named Carol Briggs, who identifies herself as a Justice Department agent and states that Maggie is a wanted felon. Lorna agrees to help Carol capture Maggie, keeping the plan a secret from Peter.

Peter arranges for Maggie to meet Abigail during a class field trip at the La Brea Tar Pits. When Maggie and the girl meet, Peter is stunned to see them wordlessly perform the cult's secret handshake. Abigail asks Maggie how she knew the handshake, and Maggie replies, "You taught it to me." At that moment, law enforcement agents burst in and apprehend Maggie. As distraught cult members accuse Peter of betrayal, he exchanges a look with Lorna, who gives a slight smile. Abigail then asks Peter who Maggie was, and he, shaken, replies that he does not know.

Sound of My Voice was named among the Top Indie Films at Festivals in 2011 on criticWIRE.