In the time that passed between the East High School winter musical (shown in High School Musical 1) and the end of the school year, the romance between Gabriella Montez (VANESSA HUDGENS) and Troy Bolton (ZAC EFRON) has blossomed.
Their respective "groups" have merged as well, resulting in a lasting friendship with composing genius Kelsi Nielsen (OLESYA RULIN) and even a budding romance between Troy's basketball teammate Chad (CORBIN BLEU) and brainy feminist Taylor (MONIQUE COLEMAN). This, along with the anticipation of a quickly-approaching summer vacation, makes even the last class of the year with drama teacher Ms. Darbus (ALYSON REED) easier to bear.
The school's obnoxious debutante-drama queen, Sharpay Evans (ASHLEY TISDALE), is resentful of all the newfound friendships and vows to break up Gabriella and Troy and restore order to the clique universe, dragging her brother Ryan (LUCAS GRABEEL) along for the ride. Knowing the gang is looking for summer jobs, Sharpay convinces her family to hire Troy at the country club they own, run by the hapless Mr. Fulton (MARK L. TAYLOR).
When Fulton hires all of Troy's friends as well, Sharpay demands that he promote Troy while doing his best to make the rest of the group miserable enough to quit. The resulting actions drive Troy further from his friends and Gabriella, even as they open doors for his future he didn't imagine were possible. Seduced by talk of college scouts, opportunities to impress Sharpay's influential father Vance (ROBERT CURTIS BROWN), and offers to practice with the local university's basketball team, Troy soon finds himself isolated and in danger of losing his best friend and his girlfriend.
Meanwhile, the East High group vows to unseat Sharpay as the reigning queen of the club's annual end-of-summer talent show. As the rift between Troy and his friends deepens, he must make hard choices about what's most important to him before it's too late, factoring in what his basketball coach dad Jack (BART JOHNSON) thinks. And with the talent show looming and the East High gang in need of a director, Ryan Evans must decide where his loyalties lie.