In The Merlin Conspiracy, Mrs. Candace is an elderly enchantress who serves as The Lady of Governance of the world of Blest -- a figure who counterbalances the male magics of The Merlin of the world with her magical talents of a more feminine cast. As such she is one of the two magically most powerful mortals in that world
Protagonist Roddy (Arianrhod Hyde) is sent to her when she badly offends her grandmother Hepzibah Dimber by trying to tell her the truth about the conspiracy and about Hepzibah's own magical tools, neither of which Hepzibah wants to believe in the slightest.
Roddy tries to explain the conspiracy to Mrs. Candace, but she meets with the same disbelief, although less of the insulted outrage. However, when Roddy adds that she's been told by The Little Person to "raise the land," Mrs. Candace tells her that on no account must she do such a shocking thing. She also takes immediate steps to send Roddy (and her friend Grundo - Ambrose Temple) to stay with Roddy's Grandfather Maxwell Hyde, trusting him to keep her sorted.
Mrs. Candace is described as rather beautiful, in a wintry, faded beauty kind of way. She evidently ran a salon in London during her youth, and has an extremely refined, posh voice and accent.
After the final confrontation of the book, it appears that Mrs. Candace will become a key figure in Roddy's future, but in the main part of the book we meet her in, she is kindly and good, but a great disappointment.