Sound of My Voice (2011)

Peter and Lorna, a young Silver Lake couple, delve into the underworld of a cult that meets in the San Fernando valley. At the center of the group is an enigmatic young woman named Maggie (Brit Marling) who never leaves her basement chamber. The members follow Maggie blindly-growing her food, obsessively sanitizing the house, giving her their own blood for transfusions. But why? We follow Peter and Lorna as they smuggle hidden cameras into Maggie's basement bent on exposing her as a charlatan and freeing the members from her spell. But when they themselves fall prey to Maggie's mind games all bets are off.