During the height of the cold war, paranoid scientist Calvin Webber (Christopher Walken) has constructed an elaborate fallout shelter underneath his family's home. As the Cuban Missile Crisis begins, Webber and his pregnant wife, fearing the worst, enter the shelter. Simultaneously, a nearby jet has engine problems, forcing the pilot to eject. When the plane crashes into the Webbers' home, the explosion is mistaken for a nuclear blast, causing Webber to seal the shelter in panic. They live there for the next 35 years, raising their son, Adam (Brendan Fraser) below ground. After years in seclusion, the family is running low on food, and so Adam is sent to the surface to attempt to purchase supplies. Upon emerging, Adam finds that the city is remarkably intact. He meets and befriends several individuals with his naive charm, including Eve (Alicia Silverstone), who he enlists to help him purchase supplies. During their shopping excursions, the two fall in love, and she learns of Adam's sheltered life. After eventually discovering that there was no nuclear holocaust, Adam returns to the shelter to introduce Eve to his parents and to attempt to ease them back into a normal life.