There is a river called Bok Chitto that cuts through Mississippi. In the days before the War Between the States, in the days before the Trail of Tears, Bok Chitto was a boundary. On one side of the river lived the Choctaws, a nation of Indian people. On the other side lived the plantation owners and their slaves. If a slave escaped and made his way across Bok Chitto, the slave was free. The slave owner could not follow. That was the law. Martha Tom, a young Choctaw girl, knows better than to cross the river, but one day, in search of blackberries, she disobeys her mother and finds herself on the other side. Thus begins the story about seven slaves who cross the big river to freedom, led by a Choctaw angel walking on water.