In the year 2015, Demon Princess Elzebub has awakened from 10 million years of domancy. She plots to conquer the Earth. She destroys a few major cities in China to prove her power to humanity, who reacts in shock.
Demon Princess Elzebub is the leader of the Ice Age Men, who appear as Skeleton Ghosts. She has an underground base at Devil Mountain. She sends out monsters to generally mess with humanity and also to destroy the elite chinese force that is foiling her attacks. Elzebub's main henchwoman is Witch-Eye (Dana Shum).
The head of the Science Headquarters, Professor Liu Ying-de, has completed the BDX Project, a potential countermeasure against Elzebub. In the HQ's secret laboratory, he transforms Lei Ma, a high-ranking SH officer, into the bionic kung fu superhero Inframan. The solar-powered red & silver armored Inframan has both enhanced strength and combat weapons.
Once Inframan destroys the princess's various monsters, she decides to steal the professor's blueprints of Inframan in hope of discovering his weakness. Meanwhile, the professor introduces Thunderball Fists, gloves capable of destroying any substance known to man as well as covering up Inframan's weakness. The princess decides to coerce the professor. Capturing the professor's daughter, the princess blackmails the professor into creating an Inframan for her. The professor agrees to go to Mount Devil for a meeting. When the professor refuses to make another Inframan, he and his daughter are frozen. Inframan and the Science Patrol decide to rescue both which leads to the climatic battle between Inframan and Demon Princess Elzebub.
Elzebub is evenuallly killed after Infra-Man fights his way into her base and past all of her minions to destroy her in single combat.
In her monster lizard form the princess is apparently capbabl of entering the ground and causing earthquakes and disasters. She can also fly. As Infra-Man learns in their final confrontation she is also totally impervious to almost any harm, as he cuts her head off several times. However, she simply regenerates a new head and lives. He learns that she is not immune to the complete atomization of his shock gauntlets and shoots him with the solar beam.