It's difficult to say whether anyone besides fans will be drawn to Robert G. Bralver & David Ferino's at times hagiographic documentary about the late Morphine frontman, who died on a concert stage in Palestrina, Italy, in 1999, at the age of 46. But Mark Sandman's influence, at least in Boston, is still being felt, and this film explains why. The freakishness of Morphine's sound — drums, baritone sax, and two-string slide bass — combined with Sandman's own persona as "The King of Cool" to create something special. The fluidly edited mix of interviews, concert footage, TV appearances, and family home movies is complemented on the soundtrack by the music of Morphine and Sandman's earlier, blues-based band, Treat Her Right. We also learn of the role that the early deaths of Sandman's two younger brothers might have played in propelling his own ambition. In the end, this is a moving portrait of a man working hard at being an artist — and succeeding.