It is needed to be said that there are many Bible references in the film. For example, Joh Fredersen's tower refers to the biblical tower of Babel, life in the underground is basically Hell on earth, and the upper ground Metropolis reminds of Paradise and it's gardens. It is not a coincidence. The main idea of the film is reflected in its epigraph which is taken from the Bible: "The Mediator Between the Head and the Hands Must Be the Heart" .
The Head is the ruling class, the Hands are the proletariat, but who is the Heart? The answer is Freder, Joh Fredersen's son, and his lover Maria, a girl from the down city who is a saintly figure to the workers. Together they decide to save the workers. But it's not as easy as it seems. The villain of the film is a frightening inventor Rotwang. Following Joh Fredersen's orders, he creates a human-like robot which looks exactly like Maria so that it could ruin her reputation among the workers and prevent any rebellion. Fritz Lang shows the false Maria as the embodiment of the Babylonian harlot and the messenger of the apocalypse. She is furious, sexual and merciless.