Rising in the skyline of Metropolis is a beautiful new complex of towers, the Ziggurat. The Ziggurat is built not only a symbol of cultural achievement, but provides the utility of harnessing the power of the sun as a weapon.
The visual splendor of the futuristic, mega-city Metropolis is only surpassed by it's world leadership in economics, technology and culture. Not far from the truth, but not the entire truth either. The totalitarian regime's blue collar force of highly advanced robot workers have displaced the working class humans from their jobs creating sprawling underground ghettos in the underground levels just above those restricted to robot workers and the great machines power the city.
Aside from the expected rise of discontent from the human workers, robots everywhere are malfunctioning and disobeying orders, nothing too dangerous it seems, but an secret anti-robot political group works tirelessly to disarm them. The human workers and their rulers have a much more violent bend than the robots.
Our protagonists Detective Shunsaku and his nephew Kinchini are on assignment from Japan to find the globally hunted mad scientist to arrest him for human rights violations. Little do our heros know that he is at work underground on the final piece of the Ziggurat a robot indistinguishable from a female human child, Tima. Tima plays the central role in the symbolism of this film, that a child like a robot can be programed for good or evil. Without the programing to become a weapon, Tima begins to develop an independent self-concept first learning the difference between "you" and "I."
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When she is told that she is the brain of a mega-weapon she cannot conceive that she is a robot, because of the empathy she has learned. This crushes her emerging ego and she like the abused child manipulated for the the purposes of the parent and not her own becomes violent and begins to destroy not only herself, but the entire world.