Karina arrives at a mansion to work as a governess for a group of singing children: Mari Nieves, Blanca, Carlos, Javier, and Santi, known in Spain as "La Pandilla". She must take care of their education, and she decides to use music to teach them. Meanwhile, the record company where the children work is busy with another project. Their biggest star Marta is preparing a song to represent Spain in the Eurovision Song Contest 1971. Carlos, the composer of the song, titled "En un mundo nuevo" ("In a new world") meets Karina in the mansion and has feelings for her, upsetting Marta, who is his girlfriend. Marta is also jealous of Karina's musical abilities. One day, when Marta catches Karina with Carlos singing a song he composed for her, she gives him an ultimatum: If Karina doesn't leave the mansion at once, she will break her contract with the record company and won't sing "En un mundo nuevo" in the Eurovision Song Contest.