Henry Bransford, youngest son of Mat Bransford, a black guide at Mammoth Cave, Kentucky, is devastated when his siblings are sold at a slave auction. Although he keeps busy at the cave, he constantly seeks information about his brother Seth who is a soldier in the Civil War. Henry is involved in a stagecoach hold-up by Jesse James, a devastating fire at the old hotel on the cave property, a period of hiding in the depths of the caverns, and finds a mummy which has been preserved in the cave. Other chapters include additional actual historical events. When he travels to Tennessee at the invitation of Mr. Emerson, one of the tourists at the cave, he finds Seth on the train. Eventually, the two of them live on the Emerson farm where Seth recuperates by tending the horses. Each boy makes his own decision regarding his future as they return to visit their family.