The U.S. have the Avengers, Canada has Alpha Flight and the Soviet Union has the Super Soldiers so Japan decides to form its own national superhero team, Big Hero 6, under the leadership of the Silver Samurai. Unfortunately, young genius Hiro's mother won't allow him to join. Hiro tracks down Sunfire only to learn that his idol's powers are quickly killing him. Big Hero 6 wants Sunfire to join but he claims that his hero days are over. Hiro returns home to find his mother gone and the villain, Everwraith, threatening to kill her unless Hiro and Baymax agree to work for him.