It took place in a women's jail, yes, but I don't think the main character or characters were political prisoners. Rather most of them were there because of the hudood ordinances which made it a jailable offense if a woman wouldn't go back to her husband's home, etc. All sorts of stories about how women came to be there -- poverty, falling in love with the wrong person, wanting to be out of an abusive situation or not wanting to marry the person their parents had chosen for them, etc..
But now that I think of it, maybe the main character was an upper class woman who got arrested during a protest of some sort.