David Kleijwigt's documentary about the band is really about Sparhawk and Parker, their marriage, their Mormon faith, Sparhawk's recent meltdown, which forced the cancellation of some tour dates, and, of course, the music of Low. Kleijwigt follows Low on a couple of tour dates, recording live performances, and everything in between, including how Sparhawk and Parker raise their kids while on tour, and Sparhawk's mixed views on America and his faith.
You May Need A Murderer is not as complete as it could be. Kleijwigt didn't shoot the making of Drums and Guns, the album on which Low is touring on during the film, and he never REALLY gets Sparhawk (or Parker) to really go into the nitty-gritty of what caused Sparhawk's problems, but he does capture a very, almost innocent, family, whose parents just happen to be rock and roller's. Sparhawk talks openly about his Mormon faith, and it is interesting to see how he lives it, and the fact that it DOES affect the decisions that he makes on a daily basis. Sparhawk and Parker choose to live their faith out, and are very serious about it, even in a world where religion and rock star do not mix. Sparhawk is earnest, and Parker is quietly supportive.
While its cinematography is cheaply DV, and often lacks character and basic technical skill, watching this husband and wife team do their thing is more than enough to keep you entranced. I don't know if you have to love Low to love the film, because I would just consider myself a "casual" fan, but it may help if you actually like "slow-core" music.