Lord of the Flies (movie, 1963)

Amidst a nuclear war, a plane carrying a group of schoolboys crash lands on a deserted island. With no adult survivors, the boys are forced to fend for themselves. At first they cooperate, but when the they split into two separate camps -- one led by the pragmatic Ralph and the other by militaristic Jack -- their society falls into disarray, leading to a disturbing examination of human nature and a chilling conclusion.