The book starts when a British plane crashes onto an island in a remote region of the Pacific Ocean. The only survivors are male children below the age of 13. Two boys, the fair-haired Ralph and an overweight boy nicknamed "Piggy," find a conch.  Ralph uses it as a horn to bring all the survivors to one area. Ralph emerges as one of the survivors' leaders during the meeting. Jack organizes his choir group into a hunting party responsible for discovering a food source. Ralph, Jack and a boy named Simon soon become the leaders. Simon, unable to bear the stress of his position, goes off to think. Alone, he finds a severed pig head. Simon envisions the pig head, now swarming with scavenging flies, and believes that it is talking to him. Simon hears the pig identifying itself as the real "Beast" and disclosing the truth about itself—that the boys themselves "created" the beast, and that the real beast was inside them all. Simon is delusional.  But Simon accidentally stumbles into a ritual dance and, mistaken for the beast, is killed by the tribe led by Jack.

Jack then orders his tribe to begin a manhunt for Ralph. Fleeing through the forest, Ralph watches as they set fire to the forest.  The fire draws the attention of a passing naval vessel. A landing party from the vessel encounters Ralph.  And this is the end.