Set in the fictional city of San Fransokyo, 14-year-old tech genius Hiro begins school as the new prodigy at San Fransokyo Institute of Technology and sets off to rebuild Baymax. However, his overconfidence and penchant for taking shortcuts leads him and the newly minted Big Hero 6 team - Wasabi, Honey Lemon, Go Go and Fred - into trouble.
As Hiro tries to find a way to connect to classmate Karmi, Go Go and Fred dive deep into comic book mythology to defeat High Voltage, a mother-daughter supervillain duo.
A purse thief gets more than he bargained for when he steals Honey Lemon's chem-lab purse and it turns him into a monster.
When supervillain Baron Von Steamer crashes Fred's Bro-Tillion, Big Hero 6 spring into action.
When Aunt Cass stumbles into an underground cooking competition, she thrives, and becomes addicted to the excitement.
Hiro, Fred, and Baymax follow GoGo into the mysterious Muirahara Woods where they get lost and everything electronic strangely fails including Baymax.
Hiro becomes demoralized when his latest school project fails spectacularly; the team must take on the incompetent villain, Globby.
After Aunt Cass nearly discovers Hiro's secret membership in the Big Hero 6, Hiro tries to set her up with someone to distract her.
Although he is obviously ill, Hiro refuses to listen to his team-mates and Baymax and only watch from afar as they fight the mercenary team Mad Jacks.
Crazy game show host Mr. Sparkles threatens to hurt Hiro's cat Mochi to force Go Go to join a game. But she is very afraid of public appearances.
Wasabi's need for order clashes with Hiro's chaotic work style when they collaborate on a school project.
Hiro becomes frustrated when he's deemed too young to attend a science workshop hosted by SFIT's most famous alumni, Dr. Trevor Trengrove.
Hiro invents a tiny robot, Mini-Max, to supervise and be a sidekick to Fred while the rest of the team is in class.
Barb and Juniper, who are upset with each other, each steal a Krei battery so that they can each look for the orb that powers them. Meanwhile, Mole gets on Fred's nerves when he steals his idea for a superhero museum and carries a fake signed photo from "Lizard Guy", resulting in Fred revealing that he is Fredzilla and part of Big Hero 6. Unconcerned with their safety, Mole blackmails them with personal favors until he decides to become a member as well with a small red variant of Fred's suit. Barb and Juniper discover that the orb was taken out of the police archive and is in Mole's possession and head to his comic book store where they make up. Fred and Go Go defeat them with the former rescuing a semi-grateful Mole. When he tries taking the orb, he gets electrified and forgets the identities of Big Hero 6.
When a monster wreaks havoc in San Fransokyo, Big Hero 6 must go on a real-life monster hunt.
Hiro is drawn back into the world of bot-fighting, where he meets Trina, a young bot-fighter.
Obake unleashes his master plan upon San Fransokyo, bringing about destruction to the entire city unless Big Hero 6 stops him once and for all.