Golding's book is very heavy into foreshadow, subtle hints the author provides in order to forewarn readers about future events. Several significant events that happen at the end of the novel are foreshadowed earlier in the story.
The first even that is foreshadowed is Piggy's death in Chapter 11, Castle Rock. Myopic and vulnerable, Piggy stands on the bridge and asks the boys whether it is better to be savages or to have reason as Ralph does. Rodger dislodges a huge boulder from atop Castle Rock that rolls down the side of the cliff, knocking Piggy into the jagged rocks beneath. This event is foreshadowed as early as Chapter 1, The Sound of the Shell, when Jack discovers a large rock and heaves it down the side of the mountain with wild delight.
Another event Golding foreshadows is Ralph's well-being. In Chapter 7, Shadows and Tall Trees, Simon predicts that Ralph will be okay when he says, "You'll get back to where you came from." At the end of the novel, we find out that Ralph does indeed end up being rescued, although perhaps he is not "all right" as he now knows the evil humankind is capable of.
In the latter event of foreshadowing, readers can infer that something malevolent will happen to Simon, since he does not include himself in the prediction of survival. What's more, all of the savage hunts, dances, and chanting culminates in Chapter 9, A View to a Death, when the group of boys dance and chant, "Kill the beast! Cut his throat! Spill his blood!" as they engulf Simon and stab him to death.
Foreshadowing, hints, and repetition all prepare the reader for the boys' degradation into savagery and violence at the end of the novel