An Nuclear warfare has seemingly destroyed most, if not all, of human civilization, leaving the Earth contaminated with radioactive fallout. The apparent single exception is an isolated box canyon, surrounded by lead-bearing cliffs, in which former U.S. Navy Commander Jim Maddison (Paul Birch (actor)) lives with his daughter Louise (Lori Nelson) in a home that he has stockpiled with supplies in anticipation of such an apocalypse. Louise is engaged to be married, but her fiancé is missing.