This film is in a league of it's own: I won't bother to re-state what every other person has already posted regarding the plot. Needless to say it makes no sense what-so-ever in the big scheme of things, but there is plenty of violence and preposterous characters such as the "Crystal Skull" liven things up no end. The best line in the whole film has to be "We can't move; we're immobilised" (by an invisible force field), so how come he can still move his jaw to speak? As I say ultimately in a league of it's own and one of the best examples of how practically any script was considered during the 80's as a potential blockbuster!