The thing that separates Trouble the Water from the many other documentary films to come out of Hurricane Katrina and its aftermath are its "stars." Filmmakers Carl Deal and Tia Lessin stumbled into a gold mine when they found Ninth Ward residents Kimberly Roberts, an aspiring rapper, and her husband Scott. It is their camcorder that captured the unfolding disaster there, as it happened.

"Aspiring rapper" is probably a generous description of Kim. She's a poor woman with a camcorder, one she takes around her neighborhood, chatting up the locals who are staying to ride the storm out because they have no means of evacuating. A child of about six giggles and asks, "Who's afraid of a little water?"

Kim is an authentic voice, funny, profane, with a thick accent and an instinctual grasp that something bad is going to happen and that it ought to be documented.

"It is going to be a day to remember," she says. Tape everything, she tells Scott, so "maybe we can sell it to the white folks [TV news]."

She wanders through the shotgun houses of the Ninth Ward, then back to her own to await her fate.

Lessin and Deal, who shot some post-Katrina footage, assembled the Roberts' tapes and TV news footage into a movie. The filmmakers wisely let Kim, Scott and the people they meet tell the story. The camera work is amateurish, but effective.

Others have played the pathetic 911 recordings of helpless people calling for rescue with no rescue coming. "So I'm gonna die," one caller says, with resignation. But no other film has scenes of people crowded into their attics as the waters rise. The film follows Kim and Scott as they join the mass forced migration out of town after the waters recede and goes back with them as they visit the damage and recall the things they didn't record -- a desperate attempt to get into a nearly-empty Navy base that was met with armed sailors who wouldn't let people in.

People we meet early on will not survive. Bodies are found (off camera), dogs die. If there's a serious shortcoming to the film, it is that it's pretty unemotional. You'd think a documentary about a tragedy, one experienced so personally by the folks on screen, one that takes its title from a hymn, would have more grief. But Kim and Scott roll with whatever nature and the various governments that let them down throw at them.

It's not quite a Grapes of Wrath for our times, but Trouble the Water does give a voice to people America didn't see or listen to before Katrina. Cable news may have given us the tragic pictures, but with Kim and Scott, we both see and hear, and for the first time, realize "Why?"