Big Hero 6 is a remake of the 2014 Disney film.
The film is set in a fictional futuristic hybrid metropolis called San Fransokyo (a portmanteau of San Francisco and Tokyo).
Hiro Hamada is a young genius and robotics expert who spends his time participating in back alley robot fights. His older brother Tadashi, worried that Hiro is wasting his potential, takes Hiro to the robotics lab at his school--the San Fransokyo Institute of Technology. There, Hiro meets Tadashi's closest friends: GoGo Tomago, Wasabi-No-Ginger, Honey Lemon and Fred as well as Baymax, a sweet and hilarious personal healthcare robot that Tadashi created. Hiro also meets Professor Robert Callaghan, the head of the robotics program.
Amazed by the students' projects, Hiro decides to enroll in the school. With help from Tadashi and his friends, Hiro designs his own robotics project in order to gain a personal invitation via an annual exhibition. His invention, Microbots, a type of nanorobotics which he can control telepathically through a neural-cranial transmitter, impresses Callaghan, who offers Hiro an invitation to the school. His project also impresses Alistair Krei, owner of the prestigious robotics company Krei Tech. Krei offers to buy Hiro's microbots, but Callaghan successfully convinces Hiro not to make the deal.
As they leave to celebrate Hiro's success, a fire suddenly breaks out in the exhibition hall. Tadashi rushes in to rescue Callaghan, who is still inside, but the building explodes moments later, apparently killing both Tadashi and Callaghan (off-screen). Heartbroken over the loss of his brother and best friend, Hiro shuts himself away in his room and isolates himself from others for two weeks.
One day, Hiro accidentally activates Baymax, who responded to Hiro's cry of pain. As Hiro attempts to deactivate Baymax, he discovers a single microbot that was left in his jacket. Hiro believes its movement is due to a malfunction, but Baymax believes it is trying to go somewhere. After Hiro gives a sarcastic response, the adorably naive Baymax follows the microbot to an abandoned warehouse just as Hiro catches up. There, they discover that someone has been mass producing Hiro's microbots before they are attacked by a masked man controlling the microbots telepathically. They barely manage to escape. Deducing that the masked man stole the Microbots at the showcase hall and started the fire to cover his tracks, Hiro decides to catch him and upgrades Baymax with battle armor and various fighting moves. Following their single microbot again, they find the masked man at the harbor and attempt to pull a surprise attack, but are unable to when Go Go, Wasabi, Honey, and Fred arrive in a car (because Baymax had contacted them earlier, thinking that a great way to help Hiro was to contact his friends). The masked man attacks them as they flee in the car. They land in the water and nearly drown, but Baymax floats them up to safety. Wet and freezing, Fred suggests that they rest in an enormous mansion that he reveals to be his home. After realizing that Baymax had scanned the masked man, Hiro decides to upgrade Baymax further so he can scan the entire city to find him. Hiro also upgrades his friends and provides them with supersuits of their own.
When scanning the entire city, Baymax locates the masked man on a quarantined Akuma Island off-shore from the city. There, the group discovers a former Krei Tech lab that was experimenting with teleportation technology. The test went awry when one of the portals became unstable and the human test pilot got lost and presumed died. Because of this, they suspect that Krei is the masked man. The masked man unexpectedly reappears and attacks them. They attempt to steal his mask, where they deduce the transmitter is located. Despite some difficulties, Hiro succeeds in knocking off the mask and the mysterious man is revealed to be Professor Callaghan, who explains that he survived by using Hiro's microbots to shield himself from the blaze. Upon realizing that Tadashi died for nothing, Hiro becomes enraged; he angrily removes Baymax's healthcare chip and orders him to kill Callaghan. With only the battle chip left, Baymax becomes a mindless killing machine and goes on a rampage in an attempt to kill Callaghan, who is powerless without the microbots. GoGo, Fred, Wasabi and Honey are able to stop Baymax and reinsert his chip, but in the process, Callaghan retrieves his mask and escapes. Angry at the four for preventing him from getting revenge, Hiro leaves with Baymax. Once home, Hiro attempts to remove Baymax's healthcare chip again, but Baymax objects to this, not wanting to become a mindless killing machine again, and asks him if killing Callaghan will make him feel better. To comfort him, Baymax then shows several video recordings of Tadashi during Baymax's development. A remorseful Hiro realizes that killing Callaghan is not what Tadashi would have wanted and he makes amends with his friends.
After examining more footage of the teleporter test, they discover that the test pilot was none other than Callaghan's daughter Abigail and realize that Callaghan is seeking revenge on Krei, whom he blames for her apparent demise. Using the microbots, Callaghan captures Krei and repairs the portal device so it will become unstable and destroy everything Krei loves: his business. The heroes arrive and Hiro attempts to reason with Callaghan, stating that revenge is a hollow victory. Callaghan briefly falters, but ultimately gives into his hatred and proceeds with his plan. The heroes battle him, and eventually manage to neutralize the microbots and take the transmitter from him. However, the portal remains active and is becoming increasingly unstable.
As everyone prepares to leave, Baymax detects female life signs from within the portal. Realizing that it must be Abigail in hypersleep, they rush in to save her. However, on their way out, Baymax's armor is damaged by a giant piece of debris and the only way to save Hiro and Abigail is to send them through with his rocket fist. Hiro refuses to leave Baymax behind, but Baymax convinces him that it is the only option. Baymax asks Hiro if he is satisfied with his care, to which Hiro sadly says yes and Baymax deactivates. Hiro and Abigail make it back through the portal. Callaghan is then arrested while Abigail is taken to hospital.
Later, as Hiro settles into Tadashi's old lab, he discovers Baymax's healthcare chip (which contains his entire personality and memories as well) within the rocket hand. He successfully rebuilds Baymax's body, reactivates him and they happily reunite. The six friends then continue their exploits through the city, helping those in need as the Big Hero 6.
In a post-credit's scene, Fred, back at his mansion, talks to a photo of his father, telling him he'd be proud of him. Fred accidentally opens a secret door and, upon entering, finds weapons, armor and superhero gear. His father (voiced by Stan Lee) arrives and states that they have a lot to talk about before the two embrace.
- Asa Butterfield as Hiro Hamada
- Seth Rogen as Baymax
- Dennis Oh as Tadashi Hamada
- Rinko Kikuchi as GoGo Tomago
- Donald Glover as Wasabi-No-Ginger
- Amanda Seyfried as Honey Lemon
- Cole Sprouse as Fred
- James Cromwell as Professor Robert Callaghan/Yokai
- Alan Tudyk as Alistair Krei
- Marisa Tomei as Aunt Cass
- Anna Kendrick as Abigail Callaghan
- Stan Lee as Fred's Father
- Paul Briggs as Mr. Yama
Rated PG for the same basis as the animated version.