Serena and her grandfather, Henry, visit an old home near St. Louis which has special meaning for them. The home had once been a farm at the time of the Civil War and some of their ancestors had been slaves there. Henry tells Serena the story of a slave named Thomas, their ancestor, and his friendship with Nathan Reneau, the farm owner's son.Thomas and Nathan become best friends as young boys and spend most days together playing and riding their ponies around the farm. One hot summer day a sudden flood in the creek almost takes Nathan's life. Thomas rescues Nathan and saves him from drowning. A sudden twist of fate takes Thomas away from Nathan but Nathan vows that he will find Thomas. Years go by until a day arrives when Nathan will be able to return the favor and rescue Thomas.