4 Little Girls, Spike Lee's documentary about the 1963 bombing of the 16th Street Baptist Church in Birmingham, Alabama, opens with Joan Baez's recording of "Birmingham Sunday" and the gravesites bearing the names of the four girls killed in that bombing. That's all a lot of people know of the event, other than that it served as a turning point in the civil-rights movement, and Lee's film attempts to correct that oversight. 4 Little Girls tells the story in full, with emphasis on the volatile environment leading up to the bombing. Martin Luther King called Birmingham "the most thoroughly segregated city in the United States," and within it, the 16th Street Baptist Church played a key role in the mounting protests of the early '60s. Bombing it was meant to strike a critical blow to the protesters, and part of the reason it didn't can be found in the resilience evident in interviews with the victims' families and other survivors. As emotional as most of them get, they also find a way to convey their still-strong dedication to the principles for which the four girls served as unfortunate martyrs. 4 Little Girls is an important act of historical preservation, a focused and effective film that brings back a dark, important moment in history with startling clarity.