There aren’t any blackberries on the Choctaw side of Bok Chitto, which means that Martha Tom needs to cross the river on the hidden step-stone path to find some on the slave side. But instead of blackberries, she finds Little Mo, who is a black slave, and his family. They become fast friends, often crossing the Bok Chitto to visit each other. Little Mo walks just like his father tells him through the plantation, not too fast and not too slow, and he is invisible to the plantation owners. Martha Tom is always there to guide him over the river.
One day, Little Mo learns that his mother is to be sold. Now, the law is that if the slaves can make it through to the Choctaw side of the river, then they are free. It is nearly impossible to make it through the plantation without being seen. But Little Mo has done it many times to visit Martha Tom, and when he leads his family through the plantation, not too fast, not too slow, they do indeed become invisible. Little Mo’s family cannot find the hidden steps in the river, but Martha Tom can. With the help of Martha’s Choctaw family and Little Mo’s courage, the family crosses the river, never to be seen on the slave side again.