Viewing an unwieldy topic through a narrow prism almost always yields greater insights than a sprawling overview, and prisms don’t get much narrower than the slant of Eddy Moretti and Suroosh Alvi’s arresting doc: the shifting fates and fortunes of Iraq’s only heavy-metal band, Acrassicauda, in the wake of the 2003 invasion. The four bandmates shrug off the novelty of Muslim youths moshing to Metallica covers: “We are living in a heavy-metal world,” one explains, as bombs rock the Casbah like pyrotechnics at an Iron Maiden show. It only gets heavier, as civil war forces half the band into Syria and a blast obliterates their practice space. Bassist Firas al Lateef and lead singer Faisal Talal, best friends who live 15 minutes apart in Baghdad, go six months without seeing each other because the streets are so deadly. Inspired by a Vice profile, the HD-shot doc covers a lot of ground despite (or perhaps because of) its limited focus. Along with grim data about the “brain drain” flight of Iraq’s most educated citizens (and the continuing hemorrhage of refugees into neighboring countries), it offers a gritty travelogue of bullet-riddled Baghdad, which the jittery hipster filmmakers prowl with moonlighting bodyguards whose paranoia surpasses even their own. In the process, the movie reclaims metal’s appeal to the powerless as well as its threat—when you can get shot for wearing a Slipknot T-shirt (talk about “Death, be not proud”) or speaking the English you learned off Master of Puppets, raising those devil horns isn’t an empty act of aggression. Given the courageously downbeat closing note, here’s hoping a follow-up catches Acrassicauda rockin’ the free world.