Picture this: World War III has just occurred. Due to the detonation of over four thousand nuclear bombs, the entire Northern Hemisphere is gone, with the South not far behind. In fact, a giant radiation cloud is currently heading straight toward one of the few remaining outposts of human civilization: Melbourne, Australia. It will be there in September.
What a buzzkill.
From there, we follow the lives of a handful of survivors with intersecting lives. There's Peter Holmes, an Australian naval officer who has just been assigned to the American submarine Scorpion, which is led by a fellow named Dwight Towers. Dwight was at sea when the war broke out, so he was forced take shelter in Australia knowing that his entire family has surely died. Peter invites Dwight over for a weekend get-together, where he introduces the disciplined captain to his wife Mary's friend, Moira Davidson.
As time creeps closer to September, things only get more complicated. Peter and Mary have some minor marital strife, primarily over Peter's suggestion that they euthanize their daughter if the radiation cloud reaches them. Meanwhile, Dwight and Moira are obviously way into each other, but Dwight refuses to make a move because he has the delusional belief that his family is still alive.
Although they try everything to avoid the radiation cloud—even sending Scorpion halfway across the world to perform scientific research—there's nothing that can be done. When the radiation finally hits, however, each character meets his or her end with some degree of acceptance. Peter and Mary die knowing that they loved each other and their daughter. Dwight dies knowing that he stayed loyal until the bitter end. And Moira dies knowing that she got as close to Dwight as humanly possible.
Okay, we spoke too soon—now that's a buzzkill.