Football captain Cristóbal discovers that his neighbor and classmate, Mariana, has changed a lot over the summer. Meanwhile, Luli is still as vain as ever and overshadows her poor brother, Fernando. As a new year begins at High School Mexico (HSM, initially interpreted), the school has announced a "Battle of the Bands" contest hosted by Jesse & Joy. Working against the clock and with limited resources, Cristobal, Mariana, and a few of their peers unite as a band. In a desperate effort, Luli dare...