Planet 51 is a funny reverse alien invasion story centered on the little green people with antennas who inhabit Planet 51, and who live in fear of being invaded by beings from another planet.

When Astronaut Captain Charles "Chuck" Baker lands his spaceship, thinking that the no-one lives there, the inhabitants’ paranoia is unleashed and the real adventure begins. Lem, a young resident on Planet 51, who is fascinated by space the world outside, will help Chuck try to escape from the authorities, recover his spaceship and return home.