In the metropolis of San Fransokyo (crossing of San Francisco and Tokyo), lives Hiro Hamada, who learns to take advantage of its ability thanks to his brilliant brother Tadashi and his friends also brilliant: the adrenaline seeker GoGo Tamago, meticulous in cleaning-No-Ginger Wasabi, the genius of chemistry Honey Lemon and Fred comics fan. When after a devastating turn of events, are involved in a dangerous conspiracy that takes place in the streets of San Fransokyo, Hiro uses his closest friend: a robot named Baymax, and transformed the group into a band of heroes last technology determined to solve the mystery.