A flying saucer lands in a park in Washington D.C. and an alien, very similar to a human being and accompanied by a giant robot, steps out from the spacecraft. After a welcome that can be defined as anything but friendly, the alien announces his intention to hold a dialogue in the presence of all the governing heads of state of the planet.

Due to the fact that the politicians cannot agree amongst themselves, the alien turns to a congress of scientists and after various complex vicissitudes, the alien finally announces to the world that his race is "keeping an eye on us." Therefore, we humans should not even attempt  to export into space our aggressiveness, as his race would make sure that we most certainly will come to regret that action. That said, the alien returns to his spacecraft and returns back home, but not until he has had the opportunity to thank the few people who tried to help him on his short stay on this planet.

In short this movie benefits from a very simple, almost elemental, and linear plot bereft of frills, and even the special effects are not numerous, nor are they especially exceptional. Yet this tale of an ultimatum to our planet succeeds, thanks to a simplicity that is almost crystalline, to earn an honored place among the all time masterpieces of science fiction cinema.

It would seem at first sight that this film's notable success is due the protagonist representing a truly great novelty for the era: An alien who is wise and good and just like us in almost every way. However, the fact remains that this film, like its contemporaries, is typical of the paranoia of the Fifties. Even if the alien is not the usual monster thirsting for blood his admonitions, as beneficient as they may seem on the surface, are clearly threatening. They are spying on us, they can control us, and if they so wanted, they could destroy us.

In fact, the real aim of the film is to show an alien who is absolutely equal to us (a character which Michael Rennie brings to life in a superlative and memorable interpretation), but at the same time more wise and more aware of what he is doing. In contrast to the self-assuredness and tranquillity of the alien, humanity finally appears for what it truly is: not a band of heroes willing to sacrifice themselves to immolation in order to save our innocent world from the monster who has come from outer space to ravage our planet, but a tribe of primitives who are selfish, cynical and often stupid. Seen in this light, the film takes on a completely different meaning, freed from the restricted field of science fiction in order to convey universal values and a powerful emotional impact. While essentially pessimistic  the story suggests that there very well may be a light at the end of the tunnel because a few are successful among the humans to demonstrate friendship to the alien, to understand him and to help him. It turns out that these people happen to be a child, a woman, an old man: the very people who, in our society, are more often than not marginalized.

It is no coincidence that this film was directed by one of the most notable and capable Hollywood filmmakers: the great Robert Wise, who went on much later to direct The Andromeda Strain and the first Star Trek motion picture.

1951: The day the Earth stood still

Directed by
Robert Wise
 
Screenwriting by
Edmund H. North (for the screenplay)
Harry Bates (for the story)

Cast 
 Klaatu - Michael Rennie
 Helen Benson - Patricia Neal
 Tom Stevens - Hugh Marlowe
 Prof. Jacob Barnhardt - Sam Jaffe
 Bobby Benson - Billy Gray
 Mrs. Barley - Frances Bavier
 Gort - Lock Martin
 Army Captain (not shown in the credits) - Holly Bane