The movie is about a group of British schoolboys, each schoolboy designated with a certain part of the human psyche(the entire story by William Golding is a mind experiment) who crash on a deserted island during a nuclear war and have to survive on their own without adult supervision. The protagonist of the movie is Ralph(representing democracy and incorruption) who tries to form a functional society on the island, maintain a signal fire for rescue and survive. His sidekick is Piggy, a spectacled fat boy(representing loyalty and intelligence) who becomes his advisor. His other friend/ally/something is Simon(representing innocence, Jesus Christ and the inner truth that we know exactly what we're becoming yet choose to ignore it), a loner and a friend of nature. The main antagonist is Jack(representing corruption and totalitarianism) and his underused sidekick is Roger(he represents evil and sadism but is relegated to a background character).
In the story, the boys crash on a tropical island. Ralph and Piggy find a conch and use it to summon everyone else. About 20-30 kids ranging from ages 7-12 show up, including a school choir led by Jack. To begin their makeshift society, the group chooses Ralph as chief over Jack(mainly because he has the conch, which represents order)whilst Jack and his choir are designated as hunters. Ralph also starts a signal fire on the mountain with Piggy's glasses(due to their ability to create fire, they represent power) they construct shelters on the beach. Things go fine for some time until Jack's passion for hunting pigs costs them a chance to be seen by an airplane when Jack lets the fire go out and his bloodthirst eventually leads him to leave the group to begin his own tribe of "fun and feasts". As he can provide people food, the people start coming to him. Also, the group begins whispering of a "beast"(a representation of superstition and fear I believe) that Jack believes he can protect them from by offering the Beast the head of a pig. The Beast's existence is confirmed when the group finds what is really the corpse of a parachutist on top of the island. Simon, an intelligent young boy finds out the truth: that the beast is merely imagination and the boys are turning savage by their own nature. He returns to the beach to tell them this, yet is brutally murdered(mistaken for the Beast himself). One by one, the boys all go to Jack leaving Ralph, Piggy and Samneric(twins who represent society) alone and open to attack from the mad tribe at any time. Jack eventually steals Piggy's glasses to make fire and Ralph's little group goes to him to a showdown. This doesn't go well as Roger murders Piggy(and destroys the conch) and Samneric are captured and tortured to join Jack's tribe. Ralph himself is ultimately hunted by the tribe who sets fire on the island.
In the last moment, rescue(who saw the island on fire) finally comes and everyone revert back to their original personalities.
As can be seen, the movie is highly symbolic and a psychological experiment which seems to confirm Golding's hypothesis that humanity is cruel and evil by its very nature and that its "goodness" is learned and artificial. I for one believe otherwise yet the movie still intrigues me. I recommend it to all people over 14 as it'll surely give you something to think about.