Build a movie plot around this: What ship leaves Australian waters? USS Sawfish

During 1964, in the months following World War III, the conflict has devastated the Northern Hemisphere, polluting the atmosphere with nuclear fallout, killing all life there. Air currents are slowly carrying the fallout south; the only areas still habitable are in the far reaches of the Southern Hemisphere.From Australia, survivors detect an incomprehensible Morse code signal coming from the West Coast of the United States. The last American nuclear submarine, USS Sawfish, under Royal Australian Navy command, is ordered to sail north to the United States to attempt to make contact with the sender of the Morse signal. The submarine is commanded by Captain Dwight Towers (Gregory Peck), who must leave his new friend, the alcoholic Moira Davidson (Ava Gardner).The Australian government arranges for its citizens to receive suicide pills or prepared injections so they may end things quickly before there is prolonged suffering from radiation sickness. An Australian naval officer, Peter Holmes (Anthony Perkins) and his wife, Mary, who is in denial about the impending disaster, have a baby daughter. Assigned to travel with the American sub for several weeks, Peter tries to explain to Mary how to euthanize their baby and then kill herself in case he is not yet home when the end comes; Mary reacts very emotionally at the prospect of killing her daughter and herself.One scientist's theory is that the radiation level near the Arctic Ocean could be lower than that found at the mid-Northern Hemisphere, which might indicate the radiation could disperse before reaching the Southern Hemisphere. The theory is to be explored along with the submarine's main mission. After sailing to Point Barrow, Alaska, they determine that radiation levels are, on the contrary, intensifying.The next day, the Sawfish arrives in the San Francisco Bay Area, just off San Francisco. Through the periscope, Captain Towers sees that while the city has escaped nuclear annihilation due to anti-missile defenses during the war, there appears to be no...