Under the pretense of having a picnic, a geologist (John Meillon) takes his teenage daughter (Jenny Agutter) and six-year-old son (Lucien John) into the Australian outback and attempts to shoot them. When he fails, he turns the gun on himself, and the two city-bred children must contend with the harsh wilderness alone. They are saved by a chance encounter with an Aborigine boy (David Gulpilil) who is on a "walkabout," a ritual separation from his tribe. The boy shows them how to survive, and, in the process, underscores the disharmony between nature and modern life.