Kreton (Jerry Lewis) is an alien from outer space who is fascinated by human beings. He decides to come to Earth for an extended vacation and becomes friends with a suburban family. Along the way he falls in love with their daughter (Joan Blackman). However, there is a force field around him that prevents any physical contact as his race has abolished any form of affection. After petitioning the superiors of his planet, he is made human. At first he is happy, but he comes to realize that being human isn't always happy: it comes with other less desired emotions such as sadness and jealousy. He decides that those emotions are not worth the trouble and he returns to his own planet.