In 1962, Major Hank Marshall (Jones) and his wife, Carly (Lange), are having marital problems because of the pressures of his job and her mental illness. Hank is a nuclear engineer who favors underground nuclear testing, an initiative code-named "Blue Sky", as opposed to above-ground, open-air detonations. Carly is a free spirit who appears to be mentally unbalanced and who is slowly being suffocated by domestic torpor and encroaching age. Her behavior embarrasses him, especially given the restrictions that prevail within a military base. Their move from Hawaii to an isolated base in Alabama alarms their oldest daughter, Alex (Locane), and sends Carly into a violent tantrum.