Of all the divisions in America, none is as insidious and destructive as racism. The documentary “The Long Shadow” takes an uncompromising look at America’s original sin—slavery—and traces its history from the country’s founding to the racial divisions that still plague us in the present day. Director Frances Causey and producer Sally Holst, both privileged daughters of the South, were haunted by their families’ slave-owning pasts. They grew up in a time when white superiority was rarely questioned, and challenging this norm was often met with deadly consequences.