In Rockwell, Maine, a local fisherman comes into the diner where Annie Hughes works - with a tall tale about a huge metal man falling into the sea. The only one to pay him much attention is Hogarth, Annie's son, who sets out exploring to find the enormous robot. What he does find is a 50-foot giant with an insatiable appetite for metal and a childlike curiosity about its new world.
Rumors of everything from an alien invasion to a Russian secret weapon bent on destroying Rockwell soon spread through the small town. But it isn't long before the rumors turn into paranoia -- the situation escalates and the possible destruction of Rockwell looms. Hogarth turns to his friend, the Iron Giant, who ultimately finds its humanity by unselfishly saving the town's residents from their own fears and prejudices.