In this chiller-thriller, Harry Baldwin (Ray Milland), his wife (Jean Hagen) and their two kids (Frankie Avalon, Mary Mitchel) are heading to the mountain for a weekend of fishing as they see a mushroom cloud forming over the Los Angeles skyline. With the highways and towns jammed by panicking motorists, rampaging looters, heavily armed survivalist and doped-up punks, Milland and his family must battle their way to the shelter of their fishing spot to await more news about nuclear disaster.