Lord of the Flies, by William Golding, is set on a tropical island. The characters are English schoolboys who are here because their plane crashed, and the morning after the crash they begin to realize that none of the adults from the plane survived. The boys range in age from five or six to about thirteen, and they are alone on the island without any adults.
When Ralph realizes this fact, he is nearly giddy with excitement. The "delight of a realized ambition overcame him" and he stands on his head--more than once. He is thrilled with the notion at first, but as the novel progresses Ralph realizes they need help. He is the one who comes face-to-chest with the naval commander who rescues them; this adult's presence is probably the only thing that saves Ralph's life.
When Piggy realizes that there are no adults on the island, he immediately ponders the possibility of an adult from the airplane surviving the crash. Soon he kind of assumes the role of adult by asking for everyone's names and trying to keep order; however, he is quickly shouted down (and ridiculed), and his suggestions are ignored. Later in the story he will complain to Ralph that the adults back in England would be horrified to see the mess they have made of things here. (Ironically, of course, things are in as much if not more chaos back in England.)
After hearing Ralph blow the conch, Jack assumes there is an adult leader, a man who blew a trumpet. When Ralph tells Jack he was the one who blew the conch, Jack turns quickly around, looking for someone other than Ralph.
Out of this face stared two light blue eyes, frustrated now, and turning, or ready to turn, to anger.
"Isn't there a man here?"
After the choir gets settled, Jack again asks Ralph if there are any grownups on the island. When Ralph assures him there are none, Jack says, "Then we'll have to look after ourselves. " From this point on, Jack's primary mission is to provide meat, though he eventually turns into a savage.
The fourth main character, Simon, says nothing about the lack of grownups on the island.