Ever since Joshua Leonard helped reinvent indie film-making as a star of found-footage pioneer “The Blair Witch Project,” he has been something of a go-to guy for groundbreaking, no-budget cinema. Two decades on he’s at it again, in an acclaimed but deeply unsettling role as a stalker in “Unsane” — filmed entirely on an iPhone by Oscar-winning auteur Steven Soderbergh (“Erin Brockovich,” “Traffic”). “The only reason I have a career still is that we availed ourselves of new technology and unprecedented techniques 20 years ago with ‘Blair Witch,'” said Leonard, 42, enthusing about how low-fi filmmaking appeals to his impatient streak. “I think it’s the reason that I was so excited when I got called in to make this project, because I love making films much more than I love waiting to make films,” he told AFP ahead its US release on Friday. “Unsane” stars British actress Claire Foy, of the Netflix series “The Crown”, as Pennsylvania office worker Sawyer Valentini, who has left her hometown under mysterious circumstances. After an online dating encounter leaves her upset, she seeks help from a counselor at a local clinic, who tells her to sign a routine form before she leaves. Within minutes, she is committed to a mental institution against her will and pumped full of pills. A fellow patient whose background may be more interesting than he is letting on, tells her she’s been locked away as part of an insurance scam but that if she keeps her head down, she will be released within days. However when Sawyer encounters Leonard’s character, an orderly she claims has been stalking her for two years, the audience begins to question her sanity as well.