Whether you're a hardcore geek or a strict math-and-science-ophobe, Primer is a head-scratcher. Dense and complicated, the story of two engineers who accidentally invent a time machine puts a great deal of faith in its audience, plunging them into a world of coils and cables, volts and magnetic fields. What saves this Sundance favorite (it won the dramatic Grand Jury Prize at the 2004 festival) from falling victim to its own complexity is its very human heart what writer/director/star Shane Carruth is really exploring in his film is the dynamics between people, and what happens when those dynamics are tested in extreme circumstances. The relationship at the heart of Primer is between friends Aaron (the Topher Grace-esque Carruth) and Abe (David Sullivan), who come home from their white-collar day-jobs and go to work in Aaron's garage, toiling with friends Robert (Casey Gooden) and Philip (Anand Upadhyaya) to launch a cottage industry manufacturing computer diagnostic equipment. But as they strive to create something new and innovative (a type of super-conductor), it's Aaron and Abe who realize that their invention has potential beyond their wildest dreams it's a time machine. Things start out innocently enough: The friends use "the box," as they call it, to make big money on the stock market so that they'll be able to quit their jobs and live the high life for awhile. Soon, though, other ideas take hold, and it's not long before Abe and Aaron start looking at each other with suspicion and doubt. The potential of their machine is so vast that it changes both men, revealing truths that neither expected. Keeping up with all of Primer's twists and turns is a challenge especially since the audio quality isn't terrific, making it difficult to follow some of the dialogue but if you do, you're guaranteed to walk away with a lot to think about. New Line brings the film to DVD in a good anamorphic transfer (1.78:1) that highlights both its cinematographic strengths and weaknesses. Carruth, a first-time director, pulls off some lovely shots, but other scenes are grainy and under- or overlit. The stereo surround audio, as mentioned above, is also spotty (English and Spanish subtitles are available). Carruth admits in his commentary that his lack of experience meant that a large percentage of the original audio recordings were unusable; most of the film was dubbed in post-production. Extras include trailers for Primer and other New Line releases, Carruth's solo commentary, and a track he recorded with Sullivan, Upadhyaya, and a handful of other cast and crew members. Keep-case.