In a dystopian vision of the future, the bustling city of Metropolis is structured in a way that the working classes live and work beneath the ground, while the upper classes live in high rises that stretch into the sky. Metropolis is governed by Joh Fredersen, a businessman and ruler who has no interest in listening to the needs of the working class, and cares only about keeping his city running as usual.
Fredersen's son, Freder, is a young idealist who is sitting in his garden one day, when a woman from the workers' city, Maria, wanders in with a group of children. The beautiful Maria tells the children that their brothers and sisters live in the high rises of the city and that they are all connected. She is ushered away, but Freder is enchanted by her philosophy and falls instantly in love with her. He goes to the workers' city and is appalled to see the conditions, especially when he sees several lives lost in an explosion.
Freder goes to his father to question him about the hierarchy of the city and the abysmal conditions in the workers' city. Fredersen dismisses Freder's questions, and when one of his assistants, Josaphat, proves incompetent, fires him on the spot. Leaving Fredersen's office, Freder approaches Josaphat and asks for his help, telling him that he will come meet him at his apartment that evening. Meanwhile, Fredersen enlists an assistant, the Thin Man, to keep his eye on Freder.
Freder goes to the workers' city and switches places with a laborer named Georgy, giving him his clothes and telling him to go to Josaphat's apartment. When the Thin Man is watching Freder's car, he mistakes Georgy for Freder and follows him to a nightclub, where Georgy stays for the entire night.
Eventually, Freder finds Maria, who is leading a peaceful revolution in the catacombs of the workers' city. She speaks about the need for a mediator, someone who can connect the head (Fredersen's ruling class) and the hands (the working class). Freder approaches her and she declares that he is the mediator they need. She also tells the story of the Tower of Babel and warns against sin and indulgence.
Fredersen visits an old acquaintance, an eccentric inventor named Rotwang. The two of them once loved the same woman, and while Fredersen impregnated her (Freder is their son), Rotwang has set to work building a robot that will make the woman he loves immortal. After spying on the meeting that Maria leads, Fredersen commissions Rotwang to help him undermine the revolution. Rotwang agrees, but when Fredersen leaves, he reveals that he wants to undermine Fredersen's plan and destroy the entire city. He finishes constructing his robot, which he makes in the image of Maria.
The robot version of Maria is amoral and highly seductive, spending most of her time doing a seductive dance at a nightclub. Eventually, Rotwang uses the robot Maria to convince the working class to wage a destructive revolution on the whole city, shutting down all the machines and flooding the workers' city. The workers do as robot Maria says and riot, flooding the workers' city, but leaving behind their children who cry for help.
The real Maria encounters the children, and with Freder and Josaphat's help aid the children's escape from the city. After the revolutionaries charge the Heart Machine—the engine that keeps the entire city running—its operator pleads with them that they cannot destroy the machines. He tells them that Maria is a witch and must be burned at the stake, and the crowds go in search of her. When they spot the real Maria in the street, they chase her, but she manages to escape to the church. At the church, she is apprehended by Rotwang who attacks her, as the revolutionaries burn the robot Maria at the stake. Freder goes to save Maria, fighting with Rotwang along the way, and Fredersen comes to witness his son's act. After Rotwang dies, Freder embraces Maria, before uniting his father with the operator of the Heart Machine, acting as the mediator between the head and the hands of society.
