A young girl is travelling to London to find work. Arriving at the station, she meets a man who has been stabbed by a member of a gang of crooks involved with greyhound racing. She becomes a suspect, but flees the scene in order to deliver a message to the dead man's brother. She is protected from the police by a night club entertainer, who she learns is the man she is seeking.

Vicki Meredith, an American ballet student in Paris, falls in love with Randall Williams, another American studying architecture in Paree, and they set up some light housekeeping together until she learns that Randall has forgotten to mention that he has a wife back in the USA. This miffs Vicki to the point where she ups and heads for South America where she meets and falls in love with Philip Fletcher, a construction engineer from America. But he hustles off to build Boulder Dam. They meet again in New York City and discover their separation has made their love even stronger. Then, Randall and his wife show up and sophistication rears its ugly head.

When delusional madman Roxor kidnaps a scientist in hopes of using his death ray to achieve world dominance, he is opposed by Chandu, a powerful hypnotist and yogi.

In the early hours of the night, young David Maclean sees a flying saucer land and disappear into the sand dunes just beyond his house. Slowly, all of the adults, including his once loving parents, begin to act strangely.

Martin Schulz (Paul Lukas), a German/American art dealer, returns to Germany at the outbreak of World War Two, adopts the Nazi propaganda philosophy, refuses to protect the Jewish fiancee, Griselle Eisenstein (K.T. Stevens), of his son Heinrich Schulz (Peter Van Eyck), who has stayed in America to run the family business

The story of a century: a decades-long second World War leaves plague and anarchy, then a rational state rebuilds civilization and attempts space travel.