The story deals with a Chernobyl-type nuclear disaster happening on German soil. The heroine of the story is a fourteen-year-old girl who flees the contaminating cloud of radiation and experiences the ensuing breakdown of social order.

The story begins at school where Janna-Berta and the other students and teachers are alarmed of a nuclear accident in the vicinity. She returns home. Her younger brother Uli is alone because the parents are away and the grandparents on vacation. Together, they flee by bicycle, because all the neighbours have already left. They meet chaos on the roads. Uli collapses with his bicycle and is run over by a car and killed. Janna-Berta, in shock, is taken to the station in Bad Hersfeld. She wants to return to her brother to bury him, is contaminated by radiation, and collapses.

She wakes up in a provisional hospital in Herleshausen, where she witnesses the hardships of others. She learns of the extent of the disaster from television and a nurse. Her hair falls out. She makes a friend, Ayse, who later dies from radiation poisoning. Her aunt from Hamburg finds her and tells her that her parents and youngest brother, who had been with them, are dead. The news was intended to be kept secret.

Janna-Berta stays with an aunt, who is not responsive to the girl's needs and wants to return to normality as soon as possible. She moves to another aunt, Almut, who shows solidarity with the victims. When her hometown is no longer banned, she returns. On the way, she finds her brother's body and buries it. She also finds her grandparents at home. They have just returned from their vacation and cannot believe what has happened until she tells them the shocking truth.