In the towering city of Metropolis, humans live above robot laborers they blame for their poverty, and the powerful Duke Red has just completed the Ziggurat, a vast new complex. Detective Shunsaku Ban and his nephew Kenichi arrive investigating a wanted scientist, and Kenichi becomes separated with Tima, an advanced android the scientist secretly built. Unaware she is a robot, Kenichi protects Tima through the city's lower depths, while Duke Red intends to seat her at the heart of the Ziggurat's hidden weapon. The film adapts Osamu Tezuka's manga.