New England nurse Mary Phinney begins her duties in Mansion House, a hotel turned Union hospital in an occupied Southern town. Mansion House owner James Sr. struggles to preserve the family fortune as daughter Emma secretly searches for her beau.

Confederate belle Emma nurses her wounded friend. Dr. Foster wrestles with his marriage and career as Mary tries to improve her patients' lives with Samuel's help. Aurelia submits to Silas' advances in exchange for his help.

Dr. Foster confronts his family's divided loyalties when his mother and wounded Confederate brother arrive. Alice is shocked to find her fiancé, Tom, deeply changed by war. Samuel and Aurelia try to persuade a slave boy to seize a chance at freedom.

During a Union ball at their house, the Green girls and Frank initiate a daring plan to help Tom escape. Mary releases Dr. Foster, still shaky from his detox, from his “quarantine” so he can guide Samuel through a delicate operation.

The unexpected visit of a hospital inspector throws the staff into disarray. Mary feels empathy for a deserter, while Silas makes Samuel pay for his arrogance. A family tragedy forces James Sr. to take a risky step to earn his family's respect.

President Lincoln's visit sets in motion a diabolical rebel plot and offers an opportunity to free James Sr. Dr. Foster uncovers a scheme to undermine him at the expense of his patients. Aurelia recovered from her surgery makes a bold decision.