A group of school boys become abandoned on an island when their plane goes down during a fictional futuristic nuclear war. Without any adult supervision, the boys must work together in order to survive in the wild. At first the boys act civil and elect a leader, Ralph, a twelve years old boy. Ralph is adamant about setting up a smoke signal so a pair of twin boys is assigned the duty to start and watch a signal fire. Another group, the choirboys, elect themselves to become the hunters and provide meat for the group. The choirboys are led by Jack, a strong-willed twelve year. Besides these boys, there are several much younger boys about the age of six who are known as the littluns. Simon, an enlightened and spiritual boy, and Piggy, a scientific thinker, quickly become the counsels for Ralph. The boys begin to be fearful of a supposed beast in the jungle. Their fears are further fueled by the arrival of a dead man with a parachute that lands on the top of the mountain. The boys begin to see Jack as a protector and look to him for leadership, but some fear him. One day while in his hiding place, Simon sees the head of a sow mounted on a stake and becomes delusional. He believes the head is talking to him.
He decides to make his way up the mountain to investigate the beast. He finds the truth that it is merely a dead man with a parachute, no beast and proceeds to the beach to tell the others who have become complete savages partaking in daily tribal dances and even torture disobedient members. When he arrives at the beach he tries to tell the boys the truth but is mobbed and killed. Soon after, Jack’s mob grows and includes nearly every boy on the island except for Ralph, Piggy, Sam and Eric and a couple of the littluns. Jack’s tribe raids Ralph’s camp one night and steals Piggy’s glasses. The next day Ralph approaches them and asks for the glasses back. Jack’s tribe then kidnaps Sam and Eric, kill Piggy, and injure Ralph. The following day a manhunt ensues and the tribe chases Ralph with intent to kill him. Ralph is saved at the feet of a British military officer on the beach who saw the smoke signal from his ship. Ralph breaks down in tears over all that has happened.