When a major earthquake hits Los Angeles, the various residents of the city cope with the chaos and destruction. Successful architect Stewart Graff (Charlton Heston) argues with his demanding wife, Remy Royce-Graff (Ava Gardner), as the disaster hits. Later, when he checks in on his flirtatious friend Denise Marshall (Geneviève Bujold), they begin an affair. As the personal dramas continue, the city is threatened by aftershocks and possibly even greater quakes.