A very popular game show on television is much akin to the gladiator games of old. Each week there is a contestant, a prisoner serving life, that is put through a series of bondage holds that she must escape from before the allotted time. For each one she escapes it gets harder and harder with the audience voting to the way in which they will interfere with her escape next. Your character gets escapes through all of the holds given to her. In the weeks past every contestant has died trying to escape and thus earn her freedom.
After winning however she finds that she escapes one prison and is put in another. The warden is wealthy as he was the contractor who won the bid to make the prison in which the woman reside. He has therefore lots of clout with the parole board who could care less what happens to those that lose anyway. "We should have had the death penalty for them anyway." is the typical response.
He takes the prisoner who wins and points out the contract she signed means she is free to get out of prison however she is bound to the warden as his slave. The prisoner has little education so knows nothing of what she signed. The contract is ironclad, so to speak.