“Fathers for whom every revolution of a machine wheel meant gold had created for their sons the miracle of the Eternal Gardens.”

In the futuristic city of Metropolis, wealthy industrialists reign from high-rise tower complexes, while a lower class of underground-dwelling workers toil constantly to operate the machines that provide its power. Joh Fredersen is the city’s master. Joh’s son Freder idles away his time in a pleasure garden with other rich children.
Freder is interrupted by the arrival of a young woman named Maria, who has brought a group of workers’ children to witness the lifestyle led by the rich. Maria and the children are ushered away, but Freder is fascinated by Maria and goes to the machine rooms to find her.

In the machine rooms, Freder watches as a huge machine explodes, causing several injuries and deaths, after one of its operators collapses. Freder runs to tell his father. Grot, one of the foremen, arrives soon afterward to deliver maps found on the bodies of the dead workers. Angry that his assistant Josaphat has failed to be the first to bring him news of either the explosion or the maps, Fredersen fires him. Knowing that he can only go into the depths and become a worker, Josaphat attempts suicide but is stopped by Freder. Concerned by Freder’s unusual behaviour, Fredersen dispatches the Thin Man to keep track of his movements.

Returning to the machine rooms, Freder encounters the worker Georgy and strikes a deal with him to switch places. Freder instructs Georgy to go to Josaphat’s apartment and wait for him. However, while being driven away by Freder’s chauffeur, Georgy becomes distracted by the Yoshiwara bordello and spends the evening there instead. Meanwhile, Fredersen takes the maps to the inventor Rotwang in order to learn their meaning. Rotwang had been in love with a woman named Hel, who left him to marry Fredersen; she died giving birth to Freder, but Rotwang still loves her. So he has got a bust of her in his house; the bust seems Adolfo Wildt’s style.

He has since built a robot (a Maschinenmensch, or Machine-Human) to “resurrect” her. The maps show the layout of a network of catacombs beneath Metropolis, and the two men leave to investigate. They eavesdrop on a gathering of workers, including Freder, and find Maria waiting to address them.

Maria prophesies the arrival of a mediator who can bring the working and ruling classes together, and urges the workers to have patience. Freder believes that he could fill the role and declares his love for her. They agree to meet in the city cathedral the next day, then part. Fredersen orders Rotwang to give Maria’s likeness to the robot so that it can ruin her reputation among the workers, but does not know of Rotwang’s plan to kill Freder as revenge for losing Hel.

Rotwang chases Maria and kidnaps her. The next morning, the Thin Man catches Georgy leaving Yoshiwara and takes Josaphat’s address from him. Freder goes to Josaphat’s apartment in search of Georgy, but finds that Georgy never arrived. After telling Josaphat of his time in the workers’ city, Freder leaves for the cathedral but does not find Maria there. He hears her cries while passing Rotwang’s house and ends up trapped inside until the robot has been transformed into Maria’s double. Rotwang sends her to greet Fredersen; Freder finds the two embracing in his office and faints, falling into a prolonged delirium.

The false Maria unleashes chaos throughout Metropolis, driving men to murder and stirring dissent amongst the workers.

Freder recovers days later and seeks out Josaphat, who tells him of the spreading trouble. Simultaneously, the real Maria escapes from Rotwang’s house after Fredersen breaks in to fight with him, having learned of Rotwang’s treachery. In the catacombs, Freder and Josaphat find the false Maria urging the workers to rise up and destroy the machines.

When Freder accuses her of not being the real Maria, the workers recognise him as Fredersen’s son and rush him, but Georgy protects him and is killed. The workers follow the false Maria from their city to the machine rooms, leaving their children behind. They abandon their posts and destroy the Heart Machine, the central power station for Metropolis, after Grot reluctantly grants them access to it on Fredersen’s orders. As all systems above and below ground fail, Maria descends to the workers’ city, which begins to flood due to the stopped water pumps. She gathers the children and with help from Freder and Josaphat, they escape from the workers’ city as it crumbles in the flood.

In the machine rooms, Grot berates the celebrating workers for their out-of-control actions. Realising that they left their children behind in the now-flooded city, the workers go mad with grief and storm out to avenge themselves upon the false Maria, who has slipped away to join the revelry at Yoshiwara.

Meanwhile, Rotwang has fallen under the delusion that Maria is Hel and sets out to find her. The mob captures the false Maria and burns her at the stake; a horrified Freder watches, not understanding the deception until the outer covering disintegrates to reveal the robot underneath. Rotwang chases Maria to the roof of the cathedral, pursued by Freder, and the two men fight as Fredersen and the workers watch from the street.

Josaphat tells the workers of their children’s safety to stop them from harming Fredersen. Rotwang falls to his death. Freder fulfils his role as mediator by symbolically linking the hands of Fredersen and Grot to bring them together.

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