Season 4 begins with the gang sharing an emotional reunion in Miami at Ally's homecoming gig. But when Austin learns the foursome's time together is only temporary, he considers enrolling in military school.
Austin takes a job at his parents' mattress store; Ally struggles to keep up with an influx of music students.
The gang has less than one week to teach total novices how to play in a band in time for the A&A Music Factory's grand opening.
The gang's plans to enjoy their senior year together are put on hold when Austin learns that he's a credit short. Ally and Dez struggle to work together as lab partners.
Ally wants to prove to Austin that she can unlock the hidden musical talent of a new student. Trish enlists Dez to help her make a video for a book report.
Celebrity singing duo, Billie & Bobbie, perform for the kids at the A&A Music Factory with their signature niceness. Trish and Dez suspect they have ulterior motives.
When Austin and Ally are paired together in Home Ec, they get to imagine life together as a married couple. Trish helps Dez book a job directing a commercial.
Desperate to perform again, Austin begins singing at a karaoke club in disguise. Ally mentors a student with stage fright.
The gang prepares for the A&A Music Factory's first showcase. Austin wants to surprise Ally by teaching his students one of her songs.
Ally performs at an awards show but the producers worry about her dancing abilities. Becky G performs.
Ally's songbook is stolen from her school's 1970s-themed party, so the gang sets out to find the culprit.
A visit with a fortune teller convinces Austin something bad will happen with his comeback concert. Meanwhile Trish believes she is going to meet a prince.
When Trish's client Boynado threatens to split up, she searches to find a way to fix their problems. Austin and Ally try to help a former impersonator find his own voice.
Ally learns that the new woman her Dad is seeing is the mom of her nightmare student at the Music Factory.
While visiting New York, the group attends the Central Park Spook-tacular and it inspires them into telling their own scary stories.
Ally's rejection from college makes her give up her "perfect student" ways as Austin and Dez decide to ride a childhood "thrill ride" 100 times before it's shut down for good.
When a missing library book threatens to keep Ally from their graduation, Austin tries to find it. Trish fakes some memorable moments in order to get more photos in the yearbook.
One of Austin & Ally's music students is upset about spending Christmas away from her father, so the gang does everything they can to try and make her happy and realize that they're her family too.
As the rest of the group prepares for the next phase of their lives, Trish is still determining what her next steps will be.
Years after the gang has gone their separate ways, Ally, Austin, Trish and Dez meet-up and learn what they have all been up to, individually.