Isabelle meets and befriends Hugo in a train station in Paris while he is fleeing from the Station Inspector. The two quickly become close friends, and Isabelle accompanies Hugo through much of his adventure. She has a key in the shape of a heart from Jeanne Méliès and is used to make the automaton work again. They both steal things even though Isabelle always gets Hugo in trouble and Isabelle is Georges Méliès's goddaughter. She later becomes Hugo's big sister when Georges adopts him.