When Colonel Tarleton sees Mary Videaux kissing General Marion, he begins to suspect that Mary is not the Tory she claims to be. He sets a trap for her and catches her trying to pass information to the Swamp Fox. Tarleton then arrests her and has her taken to Charleston to be held.

The Swamp Fox plots to help her escape, eventually ending up at a masquerade ball that Mary has been invited to attend. Tarleton then has everyone ""unmasked"", and both Mary and Fran are taken back to the prison tower. A small group of Freedom Fighters that Marion had smuggled into the fort with him then storm the tower, and the Swamp Fox and his fiancee are freed--he to return to the fight, and she to board a ship bound for New Orleans to pass the remainder of the war.