From A Wiki of Ice and Fire
|Book(s)|| A Game of Thrones (Appears)|
A Clash of Kings (Appears)
A Storm of Swords (Mentioned)
A Dance with Dragons (Mentioned)
A Game of Thrones
Beth was present during the session of needlework with Princess Myrcella Baratheon at Winterfell. There she overheard the discussion between Sansa Stark, Jeyne Poole and Arya Stark about Prince Joffrey Baratheon.
A Clash of Kings
She is one of the prisoners at Winterfell when the castle is taken by Theon Greyjoy. Theon used her as a hostage when her father tried to take the fortress back. After Ramsay Snow's treason and Winterfell's sack by the men of House Bolton, it is not known what happened to her, though she might have been taken to the Dreadfort.