Beatrice Cahill was the sister of Grace Cahill, and the guardian of Amy and Dan Cahill after the deaths of Hope Cahill and Arthur Trent. She was their great-aunt.
Beatrice was one of three children, Grace, Fiske, and Grace, born in 1927. She was from the start the polar opposite of Grace, and preferred to not go around the world, just living a normal life. She also collected ceramic cats as a hobby. Some featured ones are: A Tail of Two Kittens, Prrrrrrima Dona, and the 9 Lives of Murry. She married Stephano Breglio (divorced in 1961), then Jean-Luc Benoit (divorced in 1973), and finally Sergei Baskov (divorced in 1981). After Hope and Arthur's death, Beatrice became the legal guardian of her great-nephew and niece, Amy and Dan Cahill. As she lived in a building that didn't allow kids, she hired a au pair to take care of Amy and Dan, and always ended up firing them. Her latest hire, Nellie Gomez was soon to make the list.
One day, Grace died, and Beatrice drove Dan and Amy to her funeral, not allowing Dan to go in a ninja suit. She drove very slowly on the way to Grace's mansion, and dropped Amy and Dan off before wandering off to talk to other older Cahill family members. She put a shovel of dirt on her sisters grave, and was invited to Grace's will reading, where William McIntyre showed a video of Grace who explained the Cahill family heritage and gave the viewers the chance to take a million dollars or hunt for the 39 Clues. Beatrice told Amy and Dan if they didn't take the money, she'd disown them. When Mr.McIntyre announced the time to decide, Beatrice was the first, taking her million. When Amy and Dan decided to hunt at the end, Beatrice's face turned purple and she stormed off out of mansion, and drove off. When the weren't at their apartment, Beatrice hired a detective and Social Services to hunt for Dan and Amy.
With her 3,024th ceramic cat, a tango dancing tabby, she became the largest ceramic cat collector in Massechutes at age 81. She was later murdered by [Nathaniel [Hartford.
Beatrice is very practical, and likes ceramic cats, and also is a very bad driver, going 25 on the highway and drifting.