Indie-pop darling Stephin Merritt is the glowering hero of this intimate and adoring documentary by Kerthy Fix and Gail O’Hara. As the prolific and eclectic songwriter for the Magnetic Fields, Merritt labored in relative obscurity until the band’s three-disc album 69 Love Songs (1999) broke through to the NPR/New York Times crowd. The filmmakers glean some insights into his curmudgeonly personality from his bandmate/manager Claudia Gonson and his obedient sidemen John Woo and Sam Davol, and there’s a brief recap of the ludicrous P.C. dustup in which critics Sasha Frere-Jones and Jessica Hopper tagged Merritt as racist because of his artistic tastes. But the documentary is most valuable for its fly-on-the-wall footage of the inventive tunesmith puttering around his apartment and drilling the band on his idiosyncratic arrangements.