What makes a person walk into a theater, church, or classroom and open fire? What combination of circumstances compels a human being to commit the most inhuman of crimes? As the nation tries to comprehend the tragic events in Newtown, Connecticut, Nova correspondent Miles O'Brien investigates theories that rampage killers are driven most of all by the wish to die, not the urge to kill. Could suicide-and the desire to go out in a media-fueled blaze of glory-be their main motivation? How much can science tell US about a brain at risk for violence? Most important, can we recognize dangerous minds in time to stop the next Newtown?