Four years after the group has separated, Austin and Ally's relationship has ended as a result of their busy schedules. Dez and Trish arrange for Austin and Ally to perform a song together on The Helen Show, hoping to reunite them. Ten years later, Austin and Ally are married and have two children. Dez has also married Carrie whilst Trish married Chuck.moreless
Austin and Ally try to help bring home the father of one of their students for Christmas, while Dez and Trish work as Santa's elves.
After Ally is rejected by choice college, she decides to slack off in school. Meanwhile, Austin and Dez learn their favorite childhood ride is about to close, so they decide to take one last ride.
Austin, Ally, Trish and Dez attend the Halloween Spooktacular in New York City, where they tell scary stories about an alien; a haunted phone operating system and a werechicken.
Austin and Ally's new student is a troublemaker and also the son of the woman dating Ally's dad.
A fortune teller predicts disaster for Austin's comeback concert; and things immediately start to go wrong.
Austin secretly performs at a karaoke club in disguise, at the risk of being found out by Jimmy Starr. Ally mentors a girl with even more stage fright than what she had.
Austin and Ally prepare a budget for Life Skills class while at the same time wondering what married life would be like for them; awkwardness ensues when Dez is hired to direct a commercial and it turns out the star is his ex-girlfriend, Carrie.
A brother/sister act want to start their own music academy; but first, they need to get rid of the competition.
Ally tries to teach a new violin student, but she and Austin soon discover she has other talents. Meanwhile, Dez helps Trish film a video book report.
As the A & A Music Factory nears its grand opening, Austin and Ally must turn a group of young students into musicians in a week's time.
After Ally, Trish and Dez tell Austin that they won't be joining him for their senior year at high school, Austin decides to enroll in military school. But when the gang changes their mind, they must stop Austin before it's too late.