What does it take to save a student? Every year, hundreds of thousands of teenagers in the United States quit high school without diplomas -- an epidemic so out of control that nobody knows the exact number. What is clear is that massive dropout rates cripple individual career prospects and cloud the country's future. At Houston's Sharpstown High, once a notorious "dropout factory," a high-stakes experiment is under way to rescue students from the edge. FRONTLINE spent a semester immersed in Sharpstown to produce a portrait of four students in crisis and the teachers, counselors and principal waging a daily, personal struggle to get them to graduation. A troubling and inspiring journey through the maze of an inner-city high school, "Dropout Nation" investigates the causes, challenges and potential solutions of a national emergency.