One of the most talked-about films at this year’s Sundance festival, writer-director Shane Carruth’s long-awaited follow-up to his micro-budget 2004 time-travel thriller Primer is even more mindbending and boldly experimental than its celebrated predecessor. Kris (Amy Seimetz), a young office worker, is kidnapped and drugged by a thief, who implants her with a strange foreign body. Released and returned to her home and job, Kris discovers that the mysterious procedure to which she has been subjected has rendered her intensely sensitive to the unceasing rhythms of the natural world: sounds, colours, even microscopic biological processes envelop her in a constant sensory wave, rendering her virtually incapable of functioning in her everyday life. She soon meets a former stockbroker named Jeff (played by Carruth), whose own speedily derailing life indicates that he might have been a victim of the same operation. Guided by passages from Thoreau’s Walden, the couple set out to unravel the mystery of their inexplicable condition. Part speculative sci-fi, part romantic thriller, Upstream Color will rank as one of the most provocative and daring American independent films of the year.