The film is a metaphor for the cold war, it depicts two neighbouring nations: peace loving Aurora (long time, I think that is what it was called) and the not so peaceful land of the Steel City. While the first is a democracy, ruled by wise and compassionate men of science, the other is an over-industrialized hell, where workers are exploited by ruthless industrialists and suffer under the iron fist of the dictator. There is no organisational decision, no time-table and plan that is not decreed by the dictator. But strange things happen in the Steel City, and Aurora decides to send a spy. Infiltrating the military complex of Steel City, he makes a horrible discovery: the dictator is planning to wipe Aurora out with a super weapon. War looms....
The film is a must see for any science fiction buff, if only for the brilliant set designs. A mix of Jules Verne and industrial design ca. 1914, it's great eyecandy. The story is easy enough to follow and comes with a few interesting surprises. If you are not into sci-fi, or into espionage thrillers, or amazing optical values, don't watch it. If you are into these, by all means do!