Gamma waves are electromagnetic waves, like radio waves but really short and therefore powerful enough to punch electrons from atoms (that’s called ionization). When an atom in a molecule loses an electron, it can cause the molecule to fall apart. When molecules in our DNA are hit by radiation and fall apart, it can lead to mutation. The idea that mutation from radiation can create superhumans like the Hulk only works in fiction because it relies on the idea that a mutation in a copy of DNA will spread throughout your body. In reality, every cell, except the red blood cells, has a copy of our DNA and a mutation that causes a Hulk mutation in your liver cell is not going to affect your other cells.
So, dousing a person in gamma waves isn’t going to make them superhumans. It will just make them get cancer or, if you douse them enough, they’ll end up like those firefighters in Chernobyl.
The dictator in The Gamma People is not aware of this. He runs a small country in the Soviet Union, and he is also a mad scientist that likes to experiment on the country’s children. He douses those kids with gamma rays and, to his defense, instead of them getting leukemia, they either turn into mindless zombie workers or super geniuses that dress and look like Hitler’s youth.
An American reporter and his British photographer end up in the country and are quick to realize something is amiss. I don’t know if the British photographer is supposed to be an offensive gay stereotype or just really British. Like was tradition, there is also a beautiful female character half the age of any adult male actor in the film.
The Gamma People was a joint venture by the USA and UK, and reeks of “them commies are up to something sinister, I tell you what” cold war fears. That’s not special, since that describes most Sci-Fi films in the 1950s. Thankfully, it’s an entertaining trope, especially when done competently and with good actors as is the case here. The film is mostly men talking and gets a bit boring, but it’s sufficiently interesting to be worthy of a watch.