Thea von Harbou adapted her own novel set one hundred years in the future about a city of machines that has divided the mental people from the physical workers.
Large machines operate with many wheels and pistons. A whistle marks a shift change of workers going in and coming out. The workers live in a city deep below the earth’s surface. Towering above the earth is the Club of the Sons with museums, sports, and gardens. Freder Fredersen (Gustave Frohlich) embraces a woman. Maria (Brigitte Helm) comes out of a school with children and shows them their brothers. Freder goes in after them and sees slaves with hands tied being pushed into a smoky portal. Then workers march in after them and care for the injured.
Freder takes a taxi to the new tower of Babel to see his father. The city has numerous cars, trains, and planes among tall buildings. Freder finds his father Joh Fredersen (Alfred Abel) dictating to secretaries. Joh asks Josaphat (Theodor Loos) why he learned of the explosion from his son, not him. Joh asks Freder why he was in the machine halls, and Freder says he wanted to see his brothers and sisters. Freder asks him if he is the brain of the city. Joh says the workers are where they belong. The chief foreman of the Heart Machine, Grot (Heinrich George) comes in and shows Joh two more “damned plans.” Joh asks Josaphat why he did not bring them and tells him to pick up his remaining wages. Freder says being dismissed by him means going below, and he runs out and stops Josaphat from shooting himself. Freder offers him a job working for him and gets his address. Freder says he is going into the depths to see his brothers. Joh tells the Thin Man (Fritz Rasp) to report to him about his son’s activities.
Freder goes through a door into a steamy factory and tries to help an exhausted worker who will not leave his machine, a clock. Freder takes over his job for a while. Worker 11811 (Erwin Biswanger) puts on Freder’s clothes and goes in Freder’s car to the address found in the clothes but then goes to the entertainment district. There in a strange house is the inventor Rotwang (Rudolph Klein-Rogge). Rotwang finds a monument to Hel, the mother of Freder. Rotwang takes Joh to see his invention of Hel as a robot. Rotwang says it was worth losing his hand to create the machine-man of the future. Joh asks Rotwang about the plans they have been finding in workers’ clothes.
Worker 11811 tells working Freder that she has summoned them again at the end of the shift. A worker replaces Freder. Rotwang tells Joh it is a plan of the 2,000-year-old catacombs below. Joh wants to know what his workers are doing there. They descend with flashlights. Freder and the workers stagger down stairs to a church where Maria is praying. Rotwang and Joh look through a hole in the wall from above. Maria tells the legend of the Tower of Babel. The minds who created it needed hands to build it and used workers; but the hands knew nothing of the creative vision. People speak the same language but do not understand each other. Maria says the head and hands need the heart as a mediator. Freder asks her where the mediator is, and she says he will come. She walks to him and calls him the mediator, and they kiss.
Joh tells Rotwang to give his robot the likeness of Maria so that he can destroy their belief in her. Rotwang sends Joh back alone. He realizes that Joh will lose his son. Maria and Freder plan to meet in the cathedral tomorrow, and they lovingly part. Rotwang follows her and shines his light on skeletons and her. She tries to run away, but the doors are closed. The Prelude has ended.
In the intermezzo Freder waits in the cathedral. A monk preaches that the apocalypse has come. Rotwang creates a robot to destroy Joh, his city, and his son. Freder goes to Josaphat’s home but cannot find 11811, who was caught by the Thin Man and sent back to work. Josaphat overcomes the Thin Man. Rotwang closes in on Maria and wants to give the machine-man her face. He grabs her as she struggles. Freder hears her and pounds on the door, which suddenly opens. He goes in, and it closes. He goes into a library, and the doors close. He goes down stairs to a room with many doors and is locked in. He finds a garment of hers and calls her name.
Rotwang has put Maria in an electronic machine, and he works on his machine-man. It gets a shining heart and her face. Freder sees a door open, goes upstairs, and sees Rotwang. He asks where Maria is, and Rotwang says she is with his father. Joh orders her to go into the depths and destroy the belief in Maria. Freder sees them and becomes delirious. He is in a bed attended by a nurse and finds an invitation from Rotwang to see an erotic dancer.
From a large cauldron rises the dancer. In bed Freder thinks the Thin Man is the preaching monk. Seeing the erotic dancing makes him delirious again while he hears the apocalyptic sermon. Then he sees the sculptures of Death and the Seven Deadly Sins begin to move. Josaphat comes to Freder with a report on the workers, who are hoping for the mediator. Men in dinner jackets fight in front of the dancer. Josaphat tells Freder of her. Freder orders Josaphat to let the workers do what they wish. Rotwang tells Maria that Joh wants the workers to use force so that he can use force against them. He explains the mouthpiece is turning the workers against her religion. The false Maria tells the workers that their time has come. Rotwang tells Maria that the robot does not obey Joh, but him. The False Maria tells the workers to destroy the machines. Freder comes in and says she is not Maria because Maria speaks of peace, not killing. The robot tells them to kill him. They fight, and a worker who looks like Freder is stabbed. The workers go to destroy the machines. Rotwang says that Freder wants to be the mediator and loves Maria, but Joh overhears him.
Joh battles Rotwang and overcomes him. The false Maria incites the workers to run into the factory. They break through the bars and rush toward the M-Machine and the Heart Machine. Joh calls Grot and orders him to open the gates to the Heart Machine, and he obeys. Grot shouts that destroying the Heart Machine will flood the City. The False Maria incites the workers, and she activates the machines. Maria arrives and sees the destruction and the flooding. Children flee, and Maria sounds a large alarm bell. Children run through the water to her. Freder and Rotwang climb up a large tube. Joh sees the City’s lights go out. The Thin Man tells him that his son is with the workers. Freder finds Maria, and they embrace. Josaphat directs the children to the air shafts. Freder and Maria help the children escape. Maria says they should take the children to the Club of the sons.
Joh asks the Thin Man where his son is, but the answer is that tomorrow thousands will ask that question. Grot asks the workers where their children are. He tells them attacking the machines could cause them all to die. They blame the witch. Meanwhile the False Maria is celebrating with revelers. The workers run out of the factory. Rotwang wakes and goes to Hel’s monument. Grot and the workers see the witch and want to burn her. Grot grabs her and drags her to a platform of furniture that is set on fire. Freder struggles to get near her. Rotwang sees her from a distance and then chases Maria. He grabs her, and she struggles, tolling a large bell. The Maria being burned is the robot. Rotwang struggles with Maria until Freder comes to fight him. Grot sees Joh kneeling in despair, watching his son. Rotwang carries Maria but lets go of her to fight Freder on a roof. Freder saves Maria and kisses her.
At the cathedral door Grot comes to Joh, Freder, and Maria. Maria asks Freder to mediate between his father, the head, and Grot, the hands, and he brings their hands together.
This early science fiction classic portrays the major class division in industrial society between workers and management. Only the love of the heart can bring them together in harmony and understanding.