Devilman and two other demons are sent to Earth to possess humans and cause chaos. Finding two Japanese families nearby when they awake from their long slumber in the Himalayas, Devilman chooses to possess Akira Fudo (his first choice, Akira's father having died from fright), and the bedeviled boy is adopted by the kindly Makimura family. Falling in love with his stepsister Miki, Akira forgets his original mission. His former demon overlord, Zenon, sends a succession of creatures to kill him, and Akira must call on his ill-gotten powers.