Various battle robots have started robbing banks throughout San Fransokyo. With many innocents getting arrested, the Big Hero 6 immediately deduce that Yama is behind it. Hiro decides to return to the bot fighting ring to find evidence only to run into Trina, a young bot fighter who Hiro helps and gains a crush on. The rest of the team grow concerned for Hiro's safety and the mission is jeopardized when Hiro gets arrested again and grounded by Cass. He manages to sneak back out and this time makes it to the finals, beating Yama. However, the team learn that Yama has an alibi and Hiro realizes that Trina is behind the thefts. They defeat her robot while she runs away and Hiro thanks his friends for sticking with him. Trina returns to her "father" Obake and it is revealed that "Trina" is in fact a robot trying to get info on Hiro.
- Ryan Potter as Hiro Hamada
- Scott Adsit as Baymax, Officer 1, Goon 2
- Génesis Rodríguez as Honey Lemon
- Khary Payton as Wasabi, Stan, Goon 1
- Jamie Chung as Go Go Tomago
- Brooks Wheelan as Fred, Saw Bot Fighter
- Diedrich Bader as Bluff Dunder, Gus, Cerberus Bot
- Maya Rudolph as Aunt Cass, Waitress
- Christy Carlson Romano as Trina
- Paul Briggs as Yama
- Andrew Scott as Obake
- Daniel Henney as Tadashi Hamada
- Charlotte Gulezian as The Ringleader
- Yama's assistant from Big Hero 6 (named The Ringleader in the film) returns in this episode.
- When Trina gives Hiro a thumbs up during his bot-fights, graffiti that reads "T+H" with a heart around it can be seen in the background.
- A reference to Walt Disney can be seen in the same scene.
- Megabot and Little Yama battle again for the first time in this episode.
- Hiro's dialogue establishes his arrest at the beginning of the movie was not the first time he'd been arrested for bot fighting.