In 1964 all life on the nothern hemisphere has been exterminated by the radioactive residue of a nuclear holocaust. Only Australia is not yet affected, but has only a few more months before the poisonous radiation will arrive.
An American submarine captain Towers and his crew, the sole remnants of the U.S. Navy, finds temporary safe haven in Melbourne where life-as-usual covers growing despair. Refusing to accept that he has lost his wife and children Captain Towers meets gorgeous but sad Moira Davidson who falls for him. The situation around them becomes more an more out of control. While some go on a nonstop binge of revelry, others eagerly consume the suicide pills being issued by the government. Scientist Julian Osborn engages in auto-racing and drinking to help him forget that he took part in building the terrible weappons responsible for the catastrophy. When the possibility arises that rains have washed the atmosphere clean in the Northern hemisphere, Towers and his men head to San Diego, where faint radio signals have been emanating.