On the Beach is a post-apocalyptic novel by Nevil Shute written in 1957 about people in Australia waiting to die of radiation poisoning after the Northern Hemisphere has been destroyed by nuclear war. The Australian survivors receive a Morse code signal from the United States and send out a submarine commanded by Captain Towers to find survivors. They arrive in Washington and find that the signal is not coming from a human after all. They return to Australia, where many families have already committed suicide.
The story is set primarily in and around Melbourne, Australia, in 1963. World War III has devastated most of the populated world, polluting the atmosphere with nuclear fallout and killing all human and animal life in the Northern Hemisphere. The war began with a nuclear attack by Albania on Italy and then escalated with the bombing of the United States and the United Kingdom by Egypt. Because the aircraft used in these attacks were obtained from the Soviet Union, the Soviets were mistakenly blamed, triggering a retaliatory strike on the Soviet Union by NATO.
There is also an attack by the Soviets on the People's Republic of China, which may have been a response to a Chinese attack aimed at occupying Soviet industrial areas near the Chinese border. Most, if not all, of the bombs included cobalt to enhance their radioactive properties.
Global air currents are slowly carrying the lethal nuclear fallout across the Intertropical Convergence Zone to the Southern Hemisphere. The only parts of the planet still habitable are Australia, New Zealand, South Africa, and the southern parts of South America although they are slowly succumbing to radiation poisoning as well. Life in Melbourne continues reasonably normally though the near-complete lack of motor fuels makes travel difficult.
People in Australia detect a mysterious and incomprehensible Morse code radio signal originating from the American city of Seattle, Washington. With hope that someone has survived in the contaminated regions, one of the last American nuclear submarines, USS Scorpion , placed by its captain, Commander Dwight Towers, under Australian naval command, is ordered to sail north from its port of refuge in Melbourne (Australia's southernmost major mainland city) to contact whoever is sending the signal. In preparation for this journey, the submarine makes a shorter trip to port cities in northern Australia, including Cairns, Queensland and Darwin, Northern Territory; no survivors are found. Two Australians sail with the American crew: Lieutenant Commander Peter Holmes, naval liaison officer to the Americans, and a scientist, Professor John Osborne. Commander Towers has become attached to a young Australian woman distantly related to Osborne named Moira Davidson, who tries to cope with the impending end of human life through heavy drinking. Despite his attraction to Davidson, Towers remains loyal to his wife and children in the United States. He buys his children gifts and imagines their growing older. At one point, however, he makes it clear to Moira that he knows his family is almost certainly dead, and he asks her if she thinks he is insane for acting as if they were still alive. She replies that she does not think he is crazy.
The Australian government provides citizens with free suicide pills and injections so they can avoid prolonged suffering from radiation poisoning. Periodic reports show the steady southward progression of the deadly radiation. As communications are lost with a city, it is referred to as being "out." One of the novel's poignant dilemmas is that of Peter Holmes, who has a baby daughter and a naive and childish wife, Mary, who is in denial about the impending disaster. Because he has been assigned to travel north with the Americans, Peter tries to explain, to Mary's fury and disbelief, how to kill their baby and herself: to take the suicide pill should he not return from his mission in time to help. The bachelor Osborne spends much of his time restoring a Ferrari racing car that he had purchased (along with a fuel supply) for a nominal amount following the outbreak of the war.
The submarine travels to the Gulf of Alaska in the northern Pacific Ocean, where the crew determines that radiation levels are not decreasing. This finding discredits the "Jorgensen Effect", a scientific theory positing that radiation levels will gradually decrease by the weather effects and potentially allow for human life to continue in southern Australia or at least Antarctica. The submarine approaches San Francisco, observing through the periscope that the city had been devastated and the Golden Gate Bridge has fallen. In contrast, the Puget Sound area, from which the strange radio signals come, is found to have avoided destruction because of missile defences. One crew member, who is from Edmonds, Washington, which the expedition visits, jumps ship to spend his last days in his home town.
The expedition members then sail to an abandoned navy communications school south of Seattle. A crewman sent ashore with oxygen tanks and protective gear discovers that although the city's residents have long since perished, some of the region's hydroelectric power is still working because of primitive automation technology. He finds that the mysterious radio signal is the result of a broken window sash swinging in the breeze and occasionally hitting a telegraph key. After a brief stop at Pearl Harbor, the remaining submariners return to Australia to live out what little time they have left.
Osborne takes his suicide pill while sitting in his beloved racing car. When Mary Holmes becomes very ill, Peter administers a lethal injection to their daughter. Even though he still feels relatively well, he and Mary take their pills simultaneously so they can die as a family. Towers and his remaining crew choose to scuttle the Scorpion in the open ocean, fulfilling a naval duty not to leave the unmanned vessel "floating about in a foreign port" after her crew succumbs to suicide or radiation poisoning. Moira watches the departure of the submarine in her car from an adjacent hilltop as she takes her suicide pill, imagining herself together with Towers as she dies.