It's 1864 and the Civil War rages on. A section of the Union Army is comprised entirely of African-American soldiers—separate and most definitely not equal. When tensions rise at an army camp in Arkansas, these brave, successful soldiers are given a new assignment. They are to accompany a research team into the Ouachita Mountains. There, it is believed, once lived a race of giants. A pair of scientists from the Smithsonian have acquired a map that leads deep into Choctaw territory and perhaps dark secrets from ancient America.