When the “Trouble the Water” directors, Tia Lessin and Carl Deal, headed to Louisiana in early September 2005, they were planning to document the return of National Guard troops from Iraq and had no intention of filming anyone directly affected by the hurricane. But that changed when Ms. Lessin and Mr. Deal met an African-American couple, Kimberly Roberts and Scott Roberts. Ms. Lessin said she and Mr. Deal, who are white, instinctively recognized that they had found their new subjects in these charismatic former residents of the Ninth Ward.

Trouble the Water opens August 22 in New York and Los Angeles with a nationwide release to follow.