Eight-year-old Elsa and her mom Isabelle, move in next to Julien, an ornery old entomologist with a lavish butterfly collection in his apartment. Her mother is hardly ever home, and Elsa soon grows attached to her neighbor. When Julien sets out on a weeklong hike in search of a rare and beautiful butterfly, Elsa hides herself in his car. Although Julien doesn’t want Elsa and her constant questions around, he begrudgingly accepts the situation and allows her to tag along with him on his expedition to the Alps, where she learns many things about the natural and the human world. When Elsa’s mother realizes her daughter is missing a few days later, a manhunt begins. Fortunately for all concerned, when the two are found Elsa explains what happens. Julien uses his new place in Elsa’s life to try to help her mother realize what her daughter needs from her.