In the 1880s, Félicie (Elle Fanning), a poor orphan girl who dreams of becoming a ballerina, but lacks formal training, runs away from her orphanage in rural Brittany (France) with her best friend, Victor (Dane DeHaan), a young inventor. Together they go to beautiful Paris, but they soon become separated, and Victor becomes an office boy in Gustave Eiffel's workshop. Félicie finds her way to the Paris Opera, where the guard catches her trespassing. She is rescued by a mysterious cleaner with a limp, Odette (Carly Rae Jepsen), who agrees to let Félicie stay with her until she gets on her feet. Odette works for both the Opera and for the cruel and imperious Régine Le Haut (Julie Khaner), a wealthy restaurant owner. While helping Odette clean, Félicie spies Regine's daughter, Camille (Maddie Ziegler), practicing ballet. Camille sees Félicie, insults her, and throws Félicie's treasured music box out of the window, breaking it. As Félicie takes it to Victor for repair, she intercepts the postman who brings a letter from the Opera admitting Camille to the celebrated school of the Paris Opera Ballet; in her anger, she hides the letter and decides to assume Camille's identity to get into the school and pursue her dream, while also getting back at Camille.