William Golding's Lord of the Flies opens in the midst of a war with a group of British schoolboys stranded on a deserted island in the middle of the ocean, with no adult supervision. Two boys, Ralph and Piggy, meet near a lagoon, and Ralph finds a conch shell while swimming. At the urging of Piggy, Ralph blows into the conch, summoning the other boys. Once everyone is assembled, they decide to hold an election. Ralph becomes chief due to his age, charisma, and role as the blower of the conch. Jack Merridew, who also sought leadership, is appointed to turn his group of choir boys into an army of hunters. The older boys—such as Ralph, Piggy, Jack, and Simon—perform the majority of the work, whereas the younger boys ("littluns") prefer to play. The littluns also become afraid of a “beast,” which the older boys dismiss as the product of nightmares.
After exploring the island, Ralph decides that the boys should try to build a fire in order to signal passing ships. The first attempt ends in disaster. The fire, lit using Piggy’s glasses, burns out of control and destroys a large part of the island, and a littlun goes missing in the blaze. After Piggy scolds them for their recklessness, the boys learn from this mistake, and Jack’s hunters agree to maintain the signal fire. However, Jack becomes increasingly obsessed with hunting, to the point of donning face paint, neglecting the fire, and squandering a potential rescue in favor of killing a pig. Ralph and Piggy scold Jack, who proceeds to hit Piggy, breaking one of the lenses of his glasses. Ralph calls an assembly in order to further scold the hunters, but Jack uses the younger boys’ fear of the “beast” to garner support for his cause.
One night, while the boys are sleeping, the corpse of a parachutist lands on the mountain where the boys make their signal fire. Samneric mistake the corpse of the parachutist for the beast. Ralph, Jack, and Roger search for the beast and investigate a new part of the island, with Jack noting its potential as a fortress. They climb the mountain and find the corpse of the parachutist, but they all flee in terror, believing it to be the littluns' beast. At the next meeting, Jack attempts to stage a coup, calling out Ralph’s cowardice while confronting the alleged beast. However, the boys refuse to vote Ralph out of office, so Jack, in tears, leaves the group. Shortly after leaving, he convinces his hunters to leave Ralph’s group entirely. They move into the fortress the boys had previously discovered, which they name “Castle Rock.” As the night goes on, most of the older boys quietly join Jack’s group.
Ralph, Piggy, Simon, and Samneric are the only “biguns” who remain in the original group. At Piggy’s suggestion, they attempt to create a new signal fire on the beach, away from where the beast was seen. Meanwhile, Jack and his hunters decide to hunt and cook a pig in an effort to tempt the rest of the boys over to their side. After brutally slaughtering a nursing sow, they mount its head on a stick as an offering to the beast. Simon witnesses the hunt from his favorite spot in the forest, and when the hunters have gone, he hallucinates having a conversation with the head, which is identified as the “Lord of the Flies.” It tells him that the beast—the brutality and fear that it represents—exists within all humans. Simon, who is epileptic, suffers a seizure. After waking up, he climbs the mountain to investigate the alleged beast himself and discovers the corpse of the parachutist. He rushes back to tell the other boys what he has discovered.
Meanwhile, Ralph, Piggy, and Samneric attend Jack’s feast. Ralph and Jack argue again about priorities, but the majority of the boys side with Jack this time. When a storm rolls in, Ralph stresses the need for shelters, but Jack distracts the boys by telling them to huddle together for a dance. As the dancing grows wilder, Simon, exhausted, emerges from the trees. The frenzied boys mistake Simon for the beast and beat him to death before he gets the chance to tell them the truth about the beast. The next day, guilt over Simon’s death plagues Ralph, Piggy, and Samneric, but they all refuse to acknowledge it, instead claiming that they each had left the feast early.
The next night, Jack’s hunters raid Ralph’s camp and steal Piggy’s glasses so that they can make fire. At Piggy’s urging, Ralph, Piggy, and Samneric go to Castle Rock to get Piggy’s glasses back. Ralph tries to assert the power of the conch, but it no longer holds sway with the other boys. Piggy appeals to their sense of morality, but they continue to side with Jack. As the hunters prepare to attack Ralph and Piggy, Roger rolls a boulder down the side of the mountain, knocking Piggy to his death and shattering the conch. Samneric are captured, and Ralph flees for his life.
Now an outcast, Ralph returns to Castle Rock, on the way passing through Simon’s favorite spot and discovering the sow’s head, now reduced to bone. He knocks it off its stick, cracking it in two and widening its morbid smile. Stealthily climbing the fort’s hill, Ralph speaks to Samneric. The twins tell Ralph they were tortured into joining Jack’s group by Roger, and they warn him that Jack is intending to hunt him down. Ralph hides nearby for the night. At dawn, as the hunters pursue Ralph, they set the forest on fire in order to flush him out of hiding. Just as the hunters close in on Ralph at the beach, a naval officer, drawn to the island by the forest fire, appears. The officer is baffled and disappointed by the boys’ savage comportment. The boys, including Ralph, burst into tears, recognizing the depravity to which they have descended and the tragedies they have wrought.