Today, America has the largest black middle class in its history, yet half of all black children are born into poverty. Have the walls of segregation tumbled down, only to be replaced by walls of class? FRONTLINE correspondent and Harvard University professor Henry Louis Gates, Jr., grapples with the issues facing the 'two nations of black America' as he takes a personal journey that measures the distance between the beneficiaries of affirmative action and those they left behind.