Mademoiselle Hubert appears in The Cahill Files: Operation Trinity and is a Vesper who came to Miss Harper's Finishing School for Girls, disguised as a teacher, to try and find out what young Grace Cahill knew about the Ghent altarpiece and then kill her, but she failed with that task. Her first name is unknown. Grace describes her as "being slightly familiar" but couldn't place her.. Mlle Hubert appears in the Top Secret section of the card Fireworks and is an alias. She appears in Part Two of the book.