Carruth uses the most mundane settings -- a garage, a suburban living room, a warehouse complex, an airport terminal -- to fashion something unnerving. Dark and unknowable things are happening just next door. At the outset, we see four guys in ties talking techno nonsense in a garage; imagine someone reading stereo instructions written by David Mamet. Even they don't seem to know what they're building. Finally the quartet whittles down to a duo, Abe (David Sullivan) and Aaron (Carruth), who come to realize that their homemade invention, cobbled together out of spare parts, turns back time.
The math is tricky -- no surprise, given that Carruth was a math major in college. When Abe and Aaron finally build a larger version of their miniature time machine, which they keep in a warehouse storage facility, they discover they can live 36-hour days; if they climb in at noon and stay in their holding tanks for six hours, they will come out at 6 a.m. (I think that's right ... huh.) At first it seems like a good idea: As long as they stay holed up in a motel room -- so no one sees them, including their future selves -- they can make extra money playing the stock market. But eventually, Abe and Aaron turn on each other. One of them, it seems, has violated their agreement not to alter the future by corrupting the past, which is a sci-fi staple -- Star Trek goes to the art house.
Come to think of it, Primer is more like Back to the Future Part II, in which Biff makes off with a sports almanac from 2015 containing all the World Series scores from 1950 to 2000. It's a paradox and a puzzle, bereft of laughs but a comedy nonetheless, and absent of tension but thrilling anyway. Things don't always make sense -- especially a party scene during which someone has to go back in time to stop a guy brandishing a shotgun -- but if you give in to the movie, it's not nonsense, either. Carruth is an elliptical filmmaker, presenting us with blanks we're either asked or allowed to fill in. That they go together a dozen different ways only heightens the experience; we're not meant only to see the movie but also to interpret it.
There is no question that it will take repeated viewings to understand Primer, to gain even a glimpse of its meaning. I've seen it half a dozen times, and I still don't think I get it. But the pleasure comes not from the deciphering of the puzzle but from the process itself. The whole movie's abuzz -- from the way it looks (jittery, kinetic but never sloppy) to the way it makes you feel, elated and confused and ready to take another hit of whatever it is Carruth's been smoking. Love it or hate it, you won't be able to leave it alone.