The main character in the tale of the Wife of Bath is a young man who, blinded by lust, rapes a beautiful young woman. His original punishment is death; however, the queen and other ladies of the court intercede on his behalf, and the decision is made that if he can answer a riddle correctly within one year, he will live. If he cannot, he will be put to death. The riddle asks what women want most in the world.
The knight travels all over the countryside looking for the answer to this question and is unsuccessful. Eventually, his year is up and he heads back to the court ready for his punishment. On the way, he sees an old woman whom he asks for help. She says that she can help him, but he must pledge himself to her forever. He agrees - mostly because he has no other choice. She shares the secret answer to the riddle with him.
Once they get to the court, the knight answers that what women really want is power over men. He is correct and his life is spared. The old, ugly woman proposes to the knight, and he grudgingly accepts.
Later that evening, he is whining in bed about his bad luck being married to such a low-born, old, ugly woman. The woman says that she could either be old and loyal, or young and beautiful, but unfaithful - she asks him to choose which he would prefer. After thinking about it, the knight allows her to choose. Because he gave her what she wanted (power), she transforms into a beautiful and loyal woman.