 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) 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.Into this natural bomb shelter stumble survivors, who by chance were inside the canyon when the atomic war occurred.