Cora is a slave on a cotton plantation in Georgia. When Caesar, a recent arrival from Virginia, tells her about the Underground Railroad, they decide to take a terrifying risk and escape. Though they manage to find a station and head north, they are being hunted. Their first stop is South Carolina, in a city that initially seems like a haven. But the city's placid surface masks an insidious scheme designed for its black denizens. And even worse: Ridgeway, the relentless slave catcher, is close on their heels.