There was a belief in medieval times that if a woman bears twins, she must have had two husbands. When a woman in a neighboring castle has borne twins, a knight’s wife from the next castle speaks slander of her—that she has had two husbands—a stain upon her honor. Ironically, this neighbor also has twin daughters and, in order to avoid the reputation of disgrace, a servant girl offers to remove one of the twin girls to an abbey far away and leaves her in an ash tree with a gorgeous cloth wrapping and a ring. The mother tells her husband that she has given birth to only one daughter. The abbess rears the separated twin.
The girl, named Frene, grows up a fair maiden at the abbey. A knight becomes enamored of her, visits the abbey where she lives and talks her into fleeing the abbey and living with him—unmarried. She takes the cloth in which she had been wrapped as a child and the ring. The time comes, however, when he needs to have a son and must be married and he has to put Frene away. Every servant in his castle is horrified at this injustice. They love and respect Frene. The knight is affianced to another---the twin sister of Frene.
When the preparations for the wedding night are made, Frene visits the prospective marriage bed of her sister (still not knowing it), and decides to add the gorgeous cloth in which as a baby she had been wrapped and placed in the ash tree. The mother views the prospective marriage bed in which her daughter will lie and discovers the cloth in which she had wrapped her separated twin child. She questions Frene, who also produces the ring. At once the mother recognizes that Frene is her twin daughter, confesses her sin to her husband, who insists that the marriage be annulled and the knight marries Frene while her sister is married to another.
All is well that ends well.
Fifty Great European Short Stories. Ed. Edward and Elizabeth Huberman. New York: Bantam Books. 1971.