By all accounts of "high school etiquette," brainy Gabriella Montez (VANESSA HUDGENS) and athletic Troy Bolton (ZAC EFRON) should run in separate circles. At least, that's the way East High School seems to be set up - different cliques, divided by different interests, rarely intermingling except to pass a bit of uninformed judgment on one another.
All that changes when Troy and Gabriella meet by chance at a New Year's Eve party, where both are tapped to enter a karaoke contest. Sparks fly, in that chaste Disney way, and Troy is thrilled a few weeks later to learn that Gabriella has been transferred to East High. When auditions for the spring musical, composed by shy Kelsi Nielsen (OLESYA RULIN) are announced, the budding lovebirds are torn between resisting their temptation to sing together again and taking a plunge out of their assumed social circles.
As they contemplate their decision, they consider a lot of variables, including how to preserve Troy's jock reputation with his best friend Chad (CORBIN BLEU) and his father (and coach), Jack (BART JOHNSON); dethroning the reigning drama club royalty, brother-sister duo Sharpay and Ryan Evans (ASHLEY TISDALE and LUCAS GRABEEL); fitting in time for Gabriella to join fellow brainiac Taylor (MONIQUE COLEMAN) in the scholastic decathlon; and outwitting batty drama teacher Ms. Darbus (ALYSON REED).
As Gabriella and Troy begin to follow their true passions, a surprising number of other students follow, revealing a host of hidden talents and toppling East High's clique structure, maybe forever.