The threads which hold urban societies together are strong yet vulnerable, like spiders' webs.

5 March. Jimmy Kemp and Ruth Beckett have their peace disturbed by fighter planes, and Jimmy changes station as his car radio reports trouble in Iran.

The first three weeks of May. With Ruth pregnant, Jimmy and Ruth plan marriage. Tensions between the United States and the Soviet Union increase with Soviet convoys entering Northern Iran and the loss of an American submarine. Local official Sutton oversees Sheffield's Civil Defence. American fighters operate from RAF Finningley, making Sheffield a potential nuclear target. Jimmy is anxious about international developments and his new responsibilities. He cheats on Ruth.

Over 21 and 22 May, British troops reinforce NATO; Ruth observes a demonstration at which a CND activist argues that nuclear expenditure restricts industry and that nobody can win a nuclear war. An ultimatum expires, resulting in a conventional air attack on Mashad base, followed by a limited nuclear exchange. This prompts panic food buying. Road blocks prevent a Sheffield resident from leaving for the countryside. Hospitals are cleared and 'subversives' arrested under the Emergency Powers Act. On 25 May, two nuclear explosions occur in the Middle East. Relocated underground, Sutton heads a poorly-trained emergency committee. As international tensions reach crisis point, people are warned to stay at home.

26 May. Public information is given on fallout. The Kemps improvise an indoor shelter, while the Becketts shelter in their cellar. Jimmy works in a timber yard as the attack warning sounds. Widespread panic ensues. The United Kingdom is hit by nuclear attack, with immediate casualties between 2½ and 9 million. In all, 3000 megatons are exchanged, with 210 megatons falling on Britain. Jimmy is last seen running through the streets looking for Ruth. People burn in the heat and buildings are destroyed or left vulnerable to radioactive fallout.

A week later, Ruth claims not to care about her baby because of the likelihood of its radioactive deformity and Jimmy's death. Jimmy's parents realise that their three children are dead. The committee, trapped beneath the collapsed Town Hall, wonder whether to waste food on dying people. Ruth removes her grandmother's corpse from the cellar, then goes outside, walking among scarred and shocked people, including a woman cradling a baby's corpse.

Darkness and freezing temperatures are caused by 100 tons of dust in the atmosphere shutting out the sun. In the next few days, Ruth visits the Kemps and finds Jimmy's mother dead, and takes Jimmy's book on birds. Soldiers guarding food stores fire CS gas at crowds, and hospitals are ill-equipped to handle the numbers of sick people.

22 days after the attack, looters have murdered Ruth's parents. Survivors are recruited for reconstruction work. Mr Kemp plays youngest son Michael's video game and cries. 10 million corpses remain unburied, with little fuel or viable burial ground.

Four weeks after the attack, armed traffic wardens guard looters in detention camps; soon, criminals face firing squads. Breaking through underground, soldiers find the committee dead. In subsequent weeks, Ruth and other refugees leave Sheffield in search of food. She is billeted with a man who evicts her once the police leave. Ruth and Jimmy's friend Bob eat a sheep in the countryside. Deaths from fallout reach their peak.

By September, six months after the attack, there have been between 17 and 38 million deaths. Survivors are told to concentrate on agriculture, but conditions prevent a harvest. Ruth works the land as people die around her. She gives birth in a barn. By May, sunlight breaks through, but with a high cancer risk.

Ten years after the attack, Britain's population, between 4 and 11 million, lives at medieval levels. The prematurely aged Ruth dies. Ruth's daughter, retarded by radiation in early pregnancy, leaves, after placing Jimmy's bird book under Ruth's pillow. With rudimentary power returning, she watches a video of children's programme Words and Pictures.

Over 13 years after the attack, Ruth's daughter is threatened by two boys who can barely speak. Together they steal bread, and one of the boys is shot. The other boy rapes her. At a later date, at a barren hospital, she gives birth to a dead and mutated baby.