Released in 1956 and it must be remembered that during the 50s there was a massive obsession with UFOs so there were a large number of alien invasion films (which would then once again be replaced by giant monsters soon after, sometimes aliens and giant monsters) well anyway onto the film.
After a bit of opening narration telling us about the UFO phenomenon we are introduced to our leads, newlywed scientists Dr Russell Marvin and Carol, in their car on the way to their next rocket launch. They are talking about how they lost contact with all the others when a flying saucer shows up behind them (dun dun duuuun) but after smoking (because this was the 50s) they tried to rationalize it until finding out they actually recorded the sound of it which becomes important later.
When trying to send off the rocket the aliens suddenly show up and they look considerably less impressive than the flying saucers, very stiffly walking with as little movement as possible compared to how alive the saucers were. It’s actually a problem I find with the movie itself. All effects other than the saucers are really… kind of bad, such as walking on the spot while the background moves – bad.
So it’s up to Dr Marvin to find out a way to defeat the aliens, while avoiding their attacks by running on the spot as the background moves very unconvincingly. But whenever those flying saucers are on the screen, the film really comes to life once again a testimony to Harryhausen’s skills.