Aliens who were once defeated or driven away from Earth by Ultraman have invaded once again. Some, having grown stronger, have returned seeking revenge against Ultraman; others have broken out of prison to retaliate against Earth; and some have come simply to make their presence known. These aliens possess a variety of formidable abilities, plunging Earth into crisis once more. At this critical moment, the Steel Dragon squad steps forward, joining forces with the returning Ultraman to fight for the safety and security of Earth.