In 2006, a nuclear war devastastes humanity, leaving only small pockets of civilization, mostly in Australia; but radioactive fallout is drifting into the Southern Hemisphere. The story centers on a love triangle among American submarine commander Dwight Towers; Moira Davidson, an Australian woman; and her former beau, cynical scientist Julian Osborne. Towers' submarine and crew survived the war and steered the vessel into Melbourne. Towers, Osborne and Australian liaison officer Peter Holmes are assigned to a submarine mission to Alaska to determine if a radio signal from Anchorage holds any hope of survivors in the Northern Hemisphere. When the mission returns with fatal news--radioactive levels are still deadly--the realization of impending doom begins to unravel the social fabric; anarchy and chaos erupt. Some choose to live their final weeks recklessly, others piously. Holmes and his wife seek solace in their love for each other as Towers and Moira try to make sense of their newfound love.