When Troy Bolton (Zac Efron) takes a trip to Colorado in his junior year of high school, he never expected to meet the girl of his dreams, Gabriella (Vanessa Hudgens). When he doesn't get a call after meeting her, he assumes she didn't want to be with him, and returns to his daily life as an East High Wildcat in Albuquerque, New Mexico.
The day after winter break, he is sitting in home room, listening to their drama teacher rant, when he notices that Gabriella has not only moved to Albuquerque, but now attends East High! The relationship blossoms, and soon they audition for the spring musical, Twinkle Town. After a long race, they finally win the part over twin pre- Madonnas, Sharpay and Ryan Evans.
The next summer (HSM 2), Gabriella and Troy secure a job at a local country club, owned by Sharpay and Ryan's parents! When Troy and Gabriella find that working life separates them, they hit a rough patch, partly caused by Sharpay's growing flirtiness around Troy. When they break-up, Sharpay is soon to snatch up Troy as her partner for the talent show. After realizing they are meant for each other, the staff of high school teens organize for Gabriella and Troy to sing together, but without Sharpay knowing! Their plan succeeds, and Gabriella and Troy are united once more for their senior year.
In their senior year as East High Wildcats (HSM 3), they have trouble accepting that they are going to split up for the years of college ahead with Troy staying in New Mexico, and Gabriella traveling away 1,053 miles to Stanford. With the help of their friends, and their drama teacher, Mrs. Darbus, they organize a spring musical to reflect their problems, growing pains, and emotions. When Troy and Gabriella split before Gabriella's early freshman orientation, things get rough before they get better. In the end, Troy chooses to go to Berkley, only 32.7 miles away from Gabriella!