Pandora betrays the Hidden One when she realizes that he will never consider her as an equal, and makes her stand with humanity. Meanwhile, Ichabod and Abbie realize that the Founding Fathers' flag--the one that Betsy created--holds the key to returning to the Catacombs and seek it out... putting a deadly guardian on their trail.

After escaping the Catacombs with the reassembled Box, Abbie and Ichabod free Pandora to help them defeat the Hidden One. However, the cure may prove worse than the disease, and Ichabod calls upon a former opponent for help.