Abigail Henderson was a slave in the Empire of Truth and Light; a fascist country that was as bad as Nazi Germany but followed Moses' instructions to the Israelites' in the Book of Numbers (31:17: Now, kill all the boys. And kill every woman who has slept with a man). After surviving a truly horrific processing, she was sold to an old man (Dr. Kurt Van Heflin) who intended her to be a companion to his blind granddaughter (Inga Van de Clerk), but, it wasn't long before she became more than just a slave; she became part of the family.
Once the Secret Police discover they've been helping the underground, they raid their home, not once but three times; each time subjecting them to more and more humiliation and torture. Finally they decide to escape. This is how they do it.