Hampton, Virginia – 1861
In the early years of the Civil War, Mary Peake, a free biracial woman, believes illiteracy is like a closed door and devotes herself to educating the children of slaves. Under a large oak tree in a secluded field, Mary prepares the children for a future when they might be free. Brutal slave patrols are in constant pursuit, determined to capture and punish her for violating Virginia law that prohibits her actions.
Meanwhile, Benjamin Franklin Butler, a discredited Union general, is banished to command nearby Fortress Monroe. When escaped slaves seek sanctuary within the fort, Butler must decide whether to defy Federal law, which requires him to return the men to their Rebel owners.
Mary seizes upon the moment to form a bond with the General. After she is viciously assaulted, Mary believes that Butler is the key for her to safely continue classes for the children, and—with growing confidence—she pursues the broader goal of ending slavery.