Set around the year 2000, a mammoth city is ruled by the super-efficient industrialist Jon Fredersen (Alfred Abel) and, on the surface, appears to be a utopian dream with wealthy inhabitants living in palatial apartments set in colossal glass and concrete spires. But underground it's a different story - armies of slaves work gruelling shifts to maintain the luxurious lifestyles of their masters. The workers, a subhuman species of sluggish creatures are led by the "saintly" Maria (Brigitte Helm), who urges them not to rebel but to wait patiently for the arrival of the "mediator". Fredersen kidnaps Maria and orders mad scientist Rotwang (Rudolf Klien-Rogge) to create a robot replica to take her place. His plan is doomed when the evil mechanical Maria incites the massed workers to revolt and destroy everything in sight...