La ragazza di carta - La Fille De Papier, by Guillaume Musso (2011, France)

Tom is a writer. A succesful writer. But when Aurore leaves him, he nearly gets to death. His two best friends (Milo, his agent, and Carole, a policewoman) do everything they can to make him reacting. The only one who can move him someway is Billie: she looks to be one of Tom's characters fallen into reality. A strange adventure begins: from USA, through Mexico and Europe ...a hunt to a book, to Aurore too... lots of events that change everyone's life. Nice.