In director Zal Batmanglij’s feature debut, co-written by him and star Brit Marling, a substitute teacher (Christopher Denham) and his recovering-party-girl partner (Nicole Vicius) attempt an undercover investigative documentary about a Los Angeles cult leader (Marling) who claims to be from the near and troubled future. Exposing fakery by way of fakery has its perils, of course, especially in America’s capital of dubious fame. Is that what this slight and somehow tensely ethereal film really is about? Trafficking in modish indie asceticism with only the subtlest of science-fiction accents, Batmanglij seems so proud of ambiguousness that he practically demands viewer ambivalence. But Marling sure knows how to create a role for herself: this delicate yet domineering fetish object, so willfully inscrutable to a culture still uneasy about making talented young women central to its entertainments. Movie appreciation requires its own kind of cult surrender, eh?