In The Merlin Conspiracy, Judith is the oldest daughter of Hepzibah Dimber, hereditary witch and head of the Dimber clan of witches. She has been favored over her sister Dora Dimber to become a member of the family witching trio. The family is raising up Judith's twins Isadora Dimber and Ilsabil Dimber to the point where Hepzibah will decide which of the two of them to keep as their third member, and which to banish.
Judith appears to be a nice enough person, but she is subservient to her mother and is also the victim of a glamor spell her daughters have cast to make her oblivious to their mischief. No matter how outrageous their activities, Judit doesn't notice any of the problems they cause. Finally, Ambrose Temple figures out how to reverse the glamor spell on both Judith and Hepzibah and they are in danger of serious punishment. However, the abduction of Judith and Hepzibah with all the other hereditary witches and wizards of England sends both daughters off to their grandfather Hyde's house, where they end up joining their cousin Roddie and her friends on a quest to defeat the conspirators and save the world. Judith, along with the other witches and wizards, is eventually rescued in the process.