"Katrina, she's a bad chick," observes Kim Rivers, 24, an aspiring rap artist (Black Kold Madina) and unassuming real-life heroine. In August 2005, as the awful hurricane battered New Orleans, Kim and her husband Scott Roberts saved lives by bringing flood victims to the attic of their house in the Ninth Ward. She is also the star, and in a way the director, of this soul-roiling nonfiction film by Carl Deal and Tina Lessin. Just before the storm, Kim had bought a video camera, which she used to document the ravages that nature and an indifferent bureaucracy can wreak. "Me and Scott, we're the last two Mohicans," she says as the street becomes a river, six, eight feet high. "We truly under siege. Nobody left with no valuables, nothin' but our lives." It's because of Kim Rivers that this record of hopelessness and heroism exists. In one of her autobiographical rap songs, she says, "I don't need y'all to tell me I'm amazin', just look at me." Seriously. Just look at the good she did, the person she is, in this movie. Amazing.