A devastating nuclear war that contaminated the northern hemisphere was preceded by a standoff between the United States and China after the latter blockaded and later invaded Taiwan. Both countries are destroyed, as is most of the world. The submarine crew finds refuge in Melbourne, Australia which the radioactive fallout has not yet reached (though radio communications with several radio operators farther north than Australia indicate that radiation has reached their countries and will be in Australia in a few months). Towers places his vessel under the command of the Royal Australian Navy and is summoned to attend a briefing, partly regarding an automated digital broadcast coming from Alaska in the Northern Hemisphere. The submarine is sent to investigate, with Towers (Armand Assante), Australian scientist Julian Osborne (Bryan Brown), and Australian liaison officer Peter Holmes (Grant Bowler) on board. En route, the submarine surfaces in San Francisco, where the Golden Gate Bridge has collapsed and the city shoreline is in ruins. A crew member who is from San Francisco abandons ship, planning on dying in his home city, and is left by his shipmates after it is argued that the length of time he has spent outside has already made him irreversibly sick with radiation poisoning.