The film is an insight into a dismal post-apocalyptic world of the future, 15 years after the "Big Death", which has killed the whole of the adult Earth's population sparing only prepubescent kids. Jeremiah is one of the many kids who have buried their parents and learnt how to survive in the merciless, practically medieval world, where there is a chance only for the strongest. This world is deprived of factories, vehicles, shops or schools. Once the kids were left without supervision, the new-found freedom got into their heads and they went berserk. Years later, they realized that they did not know how to restore the world created by their parents that they (the kids) had destroyed. Traveling from town to town, Jeremiah is looking for the mysterious "Valhalla Sector" mentioned by his dying father. Together with his new friend Kurdy, he comes to the Thunder Mountain, a secret community engaged in the search of the "Big Death" secrets and creation of the new world. Kurdy and Jeremiah agree to work for the Thunder Mountain as field investigators, on condition that they will not only look for the signs of a new "Big Death" epidemic, but also help people.