Out of the sludge of a polluted swamp rises a huge, terrifying figure: the Iron Woman, about to vent her wrath on the people who are destroying the land. Young Lucy, whose father works at a factory that contaminates the water, is the first to see the giant and tries desperately to reason with the great avenger. Lucy remembers hearing of another giant creature who also visited the earth, and about the boy, Hogarth, who befriended him. Soon she and Hogarth and the Iron Man all try to save the people from the Iron Woman's vengeance.