The storyline is about the rich living luxury while the poor work to make the wealthy live comfortably, "It is the future, and humans are divided into two groups: the thinkers, who make plans (but don't know how anything works), and the workers, who achieve goals (but don't have the vision). Completely separate, neither group is complete, but together they make a whole." (IMDB) Being controlled by Maria, working like robots, slaves, to Metropolis.
The results of such a high budgeted film was a phenomenon, "The result was astonishing for its time. Without all of the digital tricks of today, “Metropolis” fills the imagination. Today the effects look like effects, but that's their appeal."(Rogerebert)