Hiro is a young genius in a futuristic metropolis called San Fransokyo and signs up for the school’s science fair. However, a fire suddenly breaks out and kills his older brother Tadashi and devastates his microbots. As a result, Hiro shuts himself away in his room while Baymax, a robot invented by his brother, becomes his only companion. One day, Hiro and Baymax discover someone has been mass producing his microbots. Hiro, together with Baymax and his four close friends, called “Big Hero 6”, determines to uncover the mystery…

　　在未來世界的大都市舊金山，天才少年小宏參加了學(xué)校的科技展會。誰知突如其來的一場大火讓他哥哥命喪火場，也燒毀了他的發(fā)明成果。身心飽受創(chuàng)傷的小宏閉門不出，哥哥生前留下的治療型機器人大白則成為他僅有的伙伴。誰知小宏和大白竟意外發(fā)現(xiàn)有人在大量生產(chǎn)他的發(fā)明。小宏、大白與其他四位朋友組成“超能陸戰(zhàn)隊”，決定揭穿這場陰謀……