In a small, US costal town with many Spanish speakers, a motorcycle gang arrives on holiday. Also in town to try to reconnect with his pregnant girlfriend, Karen, is businessman Paul Collier. Paul and a leader of the cyclists, J.J., knew each other years before, so when the gang comes upon the couple and, led by the menacing Bunny, beats up Paul and begins a sexual assault of Karen, J.J. tries to intervene: he suggests they hold cycle-riding contests, with the winner claiming Karen (he promises, sotto voce, to set her free if he wins). After the contests commence, Paul crawls away to look for help. He meets with a shrug from a cowardly sheriff's deputy; where can he turn?
While on a fishing trip, Harry Baldwin (Ray Milland) and his family hear an explosion and realize that Los Angeles has been leveled by a nuclear attack. Looters and killers are everywhere. Escaping to the hills with his family, he sets about the business of surviving in a world where, he knows, the old ideals of humanity will be first casualties.