In 2009, more people were killed in Chicago gang-related violence than U.S. troops in Iraq and Afghanistan. This statistic could be applied to other big cities, for it's as big an epidemic as anything else in America. Powerful and heart-wrenching, "The Interrupters" captures how neighborhoods have turned into war zones and spotlights an organized effort to stop the killings. It just might be the most important film released this year. Revered documentarian Steve James ("Hoop Dreams") spent a year on the mean streets of his hometown. He and his courageous crew had remarkable access to gang turfs and put themselves in harm's way on more than one occasion. They followed three members of CeaseFire, activists committed to changing the vicious circle of violence leading to retribution leading to more violence. These ex-cons were once gang members, and spent time in prison for their actions. Today, they are "the interrupters," monitoring gang activity, mediating conflicts, and trying to anticipate violent acts before they happen. They're trusted and negotiate with rival factors to prevent more deaths. Ameena Matthews, whose father was a major gang leader, is a compelling dynamo. She knows how to talk to kids, who crave someone to listen to them. She's candid about her early days of drugs, parties, and crime. The others -- Tio Hardiman, Cobe Williams, and Eddie Bocanegra -- have been down those same paths, and eventually turned their lives around. They want to prevent urban youths winding up six feet under, and their attempts to make a difference are stirring. The riveting images and poignant words of this documentary will sear into your brain -- the innocent victims, the mourning families, the tough-talking gangbangers. Gary Slutkin, a University of Chicago professor, founded CeaseFire in 1995. He relates that crime is an epidemic that should be treated like tuberculosis. This film was screened at the Sundance Film Festival at a nearly 3-hour length, but James has edited it down to about 2 hours for wider release. Based on a 2008 New York Times Magazine article by Alex Kotlowitz, who serves as the film's producer, the effect is undeniable. James, a graduate of Southern Illinois University at Carbondale, dares to tell what's really going on, and in the process, leaves us with hope. For these persuasive messengers of change can be effective, and that's a start.