Following an aeroplane crash, a group of British schoolboys find themselves on a deserted tropical island. Two of the boys, Ralph and Piggy, find a large conch shell and use it like a trumpet to call the other survivors onto the beach. Last to arrive are Jack and a group of choirboys. After some initial discussion Ralph is elected leader and Jack is far from pleased. Jack is made responsible for organising a sub-group of hunters. While Piggy is left behind to make a list of all the other boys, Ralph, Jack and Simon set about exploring the island. As they do so they spot a wild pig and Jack says he will kill it for food but cannot quite bring himself to do so.
It becomes clear that no adults have survived so the boys will have to learn to fend for themselves. One of the concerns raised by the 'littluns' (the younger boys) is that there is some sort of beast on the island. Ralph reassures them then suggests they build a signal fire on the mountainside to attract attention. Jack takes over but does so carelessly. Having started a fire using Piggy's glasses, it gets out of control and then several boys go missing. Ralph and Piggy try to get the boys to build shelters and follow some basic rules but already the society they are trying to create is breaking down - the younger boys particularly just want to play and have fun.