Winner of the Grand Prize at Sundance last year, Shane Carruth’s Primer was the most exciting first feature by a U.S. director at the festival since Richard Kelly’s Donnie Darko in 2001. Like Kelly’s film, Primer is a muted sci-fi time-warp narrative with allegorical underpinnings, but the similarity pretty much ends there. Where Kelly’s high-school hero sacrificed himself to save his loved ones from being destroyed by a demonic rabbit, who was also his evil twin, the protagonists of Primer are bored 30-year-old engineers trying to invent some get-rich-quick gizmo in a garage. In the process, they stumble onto a device that’s too valuable to market and that will allow them to have pretty much anything they want. Since the device is a crude form of time machine, and since film itself is a kind of time machine, one can read Primer as a film that mirrors its own DIY production. Carruth spent three years teaching himself screenwriting and filmmaking from scratch. He wrote, directed, edited, and scored Primer and also played one of the lead roles. Heady is the word for the film, which doesn’t yield its narrative in a single viewing. But even more compelling than the time-warped storyline is the way, visually, every shot has the surprise and intensity of a new idea. The film feels like a succession of brainstorms, held together by a nearly subliminal overlay of sound effects and music. Carruth, his co-star David Sullivan, and the rest of the inexperienced cast handle the professional jargon as deftly as the veterans on ER. But despite echoes of La Jetee, The Killing, and various prime-time medical/crime shows, the aptly titled Primer is not a pastiche. Rather, it is evidence of a unique and unified vision.