Lucia (Delfina Varni) is an active little girl who has just lost a tooth. Her unemployed father, Santiago (Fabian Mazzei), and architect mother, Pilar (Ana Maria Orozco), reassure her that the Hairy Tooth Fairy, a mouse named Raton Perez (Alejandro Awada), would visit her that night and collect her tooth and leave some money in its place. But things dont go as planned when two scoundrels kidnap Raton and his boat to keep his fortune for themselves. After hearing the news, Lucia sets out with her cousin Ramiro (Nicolas Torcanowsky), disobeying her parents, to rescue Rotan.