Lord of the Flies, by William Golding, is set on a tropical island; the characters in the story are all English schoolboys who have been left stranded there, without any adults, after a plane crash. In the initial description of the island, Golding reminds us that there is a "scar" left by the cabin of the plane during the crash which mars the natural beauty of the island, so we are not surprised when the island is soon revealed to be less than tranquil and safe.
In chapter two, the older boys are trying to convince the younger boys that, despite the fact that they may be stuck here for quite some time, this is a terrific place to be. Ralph says:
“While we’re waiting we can have a good time on this island.”
He gesticulated widely.
“It’s like in a book.”
At once there was a clamor.
“Swallows and Amazons–”
Ralph waved the conch.
“This is our island. It’s a good island. Until the grownups come to fetch us we’ll have fun.”
Jack adds that he there is plenty of food and water then asks if anyone has discovered anything else. No one speaks, but soon the older boys realize one of the younger boys has something to say.
The older boys ﬁrst noticed the child when he resisted. There was a group of little boys urging him forward and he did not want to go. He was a shrimp of a boy, about six years old, and one side of his face was blotted out by a mulberry-colored birthmark. He stood now, warped out of the perpendicular by the ﬁerce light of publicity, and he bored into the coarse grass with one toe. He was muttering and about to cry.
This little boy finally whispers his question in Piggy's ear: he wonders what the older boys are going to do about the "snake-thing," which he also calls a "beastie." He claims to have seen it during the night, when it came toward him and attacked. In reality, the boy is obviously having nightmares featuring the hanging, looping vines of the jungle, imagining them to be beasts which are attacking him.
The result of the mulberry-birthmarked boy's question is bringing the boys' fear out in the open. We learn that all of the boys have had nightmares, and this discussion allows the boys to speak openly about their fears. It is clear that there is no physical beast on the island, but the boy's use of the word brings all their worst fears to the surface. Ralph and Jack, the two leaders on the island, will spend the rest of the novel trying to soothe and explain away those fears; Jack eventually uses those fears to maintain power, and Simon will die from the boys' unreasonable fear of imaginary beasts.
Of course, later in the chapter this same little boy is killed by a runaway fire, set by the boys themselves.--a foreshadowing of Simon's discovery that they are the beast.