Cut to the Heart finds Clara Barton working among the Gullah communities on the South Carolina Sea Islands near the mainland city of Beaufort. She is stationed on Hilton Head Island, headquarters of the Union Army's Department of the South. Waiting for the next battle to begin, Clara uses her nursing skills to care for the wounded commanding officer Colonel John Elwell. While she is there, her innate desire to investigate drives her to learn all she can about Gullah folk medicine and customs as she awaits the opportunity to return to the front lines. Off the battlefield, Clara reveals a warm and womanly side.

But there is palpable evil at work amid the isolation of the Sea Islands, and Clara soon senses it. The hidden source of the evil is a highy eccentric, egocentric, and fiercely ambitious doctor. He appears normal enough on the surface, but underneath there are more sinister forces at work. As Clara's suspicions about the strange happenings among the Gullah escalate, and the shroud of darkness begins to loom out of control, the events of history propel Clara and her nemesis toward a confrontation as old as time itself. On one side stands Clara Barton, the epitome of goodness and humanity - on the other, a sociopath who embodies the most depraved extremes of human behavior.