Hiro pursues Baymax who is in search of the reason the microbot is so active. Baymax leads Hiro to an old warehouse in a rough area of the city where they make a stunning discovery!

Hiro is surprised and puzzled to discover his microbot is shaking to seek out the other microbots that were assumed lost in the fire. As Baymax tries to help Hiro solve the puzzle, he rushes out the door to create an even bigger one!

Hiro is despondent. Tadashi is dead. So is Professor Callaghan. Hiro isn't eating or sleeping and he is running out of time to enroll for classes at SFIT after receiving the offer. But while Tadashi is gone, his latest invention -- Baymax -- isn't.

Hiro's invention is a colossal hit. It is worth a fortune and he is offered just that. Hiro must choose between instant fortune or maintaining possession and developing it at SFIT as a student there. But suddenly tragedy hits.

Hiro steps up on stage at the annual Tech Showcase to present his invention. The moment everybody has been waiting for has arrived!

SFIT holds its annual Tech Showcase with winners extended offers to attend the school. Hiro works for months on his new, secret invention. The day of the showcase has come and all Tadashi's friends and co-workers at the Institute are excited to finally see what Hiro has come up with.

Tadashi takes Hiro to his workstation and shows his younger brother a robot he's been working on named Baymax. But when Hiro learns Tadashi works with the legendary inventor Professor Robert Callaghan, he has to decide between bot fights or attending San Fransokyo Tech.

Hiro enters his older brother's "nerd lab" workplace and he is immediately captivated. Finally something that interests him! There he meets Go Go Tomago, Wasabi, and Honey Lemon, blown away by the technology inventions they were working on.

Hiro's big brother Tadashi Hamada races in on a motorbike to rescue his brother but they don't get far. The police raid the area. Poor Aunt Cass has to bail them out. Has Hiro learned his lesson?

In chapter one, the champion Yama is stunned his fighting robot meets his match in Hiro's little Megabot.