Simon wakes as a storm gathers over the island. He climbs the mountain even though he's staggering with exhaustion. He sees the "beast" and realizes that it's just a dead parachutist. He untangles the cords holding the parachutist in place, and heads down the mountain to tell the others.
Simon goes to the mountaintop, a symbolic journey, and learns the truth. Like other religious figures, Simon then seeks to spread his enlightenment to others.
Meanwhile, everyone but a few littleuns and Ralph and Piggy have gone to Jack's feast. Ralph mocks the feast as a bunch of boys "pretending" to act like a tribe. But the lure of food proves too much for Piggy, who suggests they go to the feast "to make sure nothing happens."
Piggy is betrayed by his stomach: he wants meat. But Piggy tries to hide his savage desire for food by making up "civilized" excuses for attending the feast.
Jack acts like a savage chief at the feast. His face is painted and he wears a crown of leaves. Jack commands and the other boys obey him.
The boys have traded freedom for the security of an all-powerful ruler.
When Ralph arrives, Jack asks the gathered boys who will join his tribe. Ralph says that he's still chief and has the conch, but Jack says the conch has no authority on this side of the island.
Jack claims to be beyond the conch's (civilization's) reach. He's become a savage.
It starts to rain, and Ralph laughs that Jack's tribe had no foresight to build shelters. In response, Jack whips the group into "their dance." They form a chanting circle: "Kill the beast! Cut his throat!" Roger pretends to be a pig at the center of the circle, but eventually stops. Even Ralph and Piggy press forward. The circle of boys becomes a frenzied mob.
Civilization creates security by building protective shelters. Savages do the same by forming mobs that allow individuals to forget their fears. Both strategies involve hiding from fear, from the beast within.
Suddenly, Simon staggers from the forest, shouting the news about the dead parachutist. In their frenzied dance, though, the other boys think that he's the beast. They surround him, and beat and claw him to death. The rain pours down. Wind lifts the parachutist and sails it toward the boys, who run screaming. Simon's body washes out to sea.
The Lord of the Flies' prediction comes true: all the boys murder Simon. Like Jesus Christ, he was killed while trying to deliver the spiritual truth.