Ricky returns to school for the new year to discover that his former girlfriend, Nini, is now dating E.J., whom she met at a theater camp over the summer. On her first day as the new drama teacher at East High, Miss Jenn announces that the school will be staging a production of "High School Musical: The Musical". Mr. Mazzara warns Miss Jenn of the need to be professional while at work.
Nini is inspired to audition for the musical after typically participating as a chorus member; and Ricky decides to audition in an attempt to impress Nini and rekindle their relationship.
Nini meets transfer student Gina, who intimidates her with her dance abilities. Nini boldly auditions for the role of Gabriella by singing "Start of Something New", while Ricky auditions for Troy by singing the song that Nini previously wrote for him as a declaration of her love. Upset, Nini confronts Ricky, before the cast list is posted, revealing Ricky and Nini in the lead roles of Troy and Gabriella respectively.