Detropia is word play for "dystopia," and that's the overview here of the crumbling, crime-ridden, largely unemployed phantom of a Michigan city, which has lost half its population since 1955. This documentary by Heidi Ewing and Rachel Grady, the filmmakers of Jesus Camp, makes a telling case that Detroit has gone beyond recession to a full-blown Depression, just like the 1930s. The difference, of course, is there's no FDR to bail the city out, nor an America that believes its our national duty to help. The sadness here is softened a bit by a host of appealing on-stage locals — a union president, a blues club operator, etc. — who somehow still love their town. And there's a tiny ribbon of hope: young artists from everywhere moving in, attracted by the impossible low prices for housing.