A suburban American family is en route to California for vacation. As they travel through the Nevada desert in their station wagon pulling a trailer, they decide to take a detour to look for silver in the hills, veering off the main road at the advice of a dubious gas station attendant. This ill-fated decision leads to a catastrophic event when they crash their station wagon, leaving them stranded in the remote desert. Unbeknownst to them, this area was once used by the government for nuclear testing, and the family soon realizes they are not alone. They encounter a clan of deformed and savage people, who have been living in the hills and have developed a taste for violence and cannibalism; a product of the nuclear fallout that left them isolated from civilization.

As night falls, the family's situation grows increasingly perilous. The clan begins to terrorize and torment them, exploiting the darkness and their familiarity with the terrain. The family must band together in a fight for survival, using their wits and any resources they can muster to defend themselves against the murderous inhabitants. With limited supplies and no means of communication to the outside world, the secluded desert becomes a harrowing battleground as the family faces the brutality and inhumanity of their hidden assailants.