Source: http://aliceeberti.tumblr.com/post/99583237121/all-the-langdons-co-protagonist
Katherine Solomon is a Noetic scientist; she has a lab at the New York Metropolitan. She drives a white Volvo. She is the younger sister of Peter Solomon and the aunt of the deceased Zachary Solomon.
In The Lost Symbol, Katherine joins Langdon half-way through the novel, as his deuteragonist, after he saved her life, and helps him solve the clues to find her brother before it's too late.
In the 2021 television series based on The Lost Symbol, Katherine was portrayed by Valorie Curry and she was also Peter's daughter and Zachary's sister.