A train passenger car carrying a reporter and his photographer mysteriously breaks away from its locomotive, accidentally ending up on a remote sidetrack in Gudavia, an isolated Ruritanian-style, one-village Eastern Bloc dictatorship. The newsmen discover a mad scientist using gamma rays to turn the country's youth into either geniuses or subhumans, all at the bidding of an equally mad dictator.

References:
https://en.wikipedia.org/wiki/The_Gamma_People