The year 1945. A married couple with two children, 14-year-old Ludwik and 9-year-old Hanna, arrive in Krakow from Lviv. Ludwik begins his studies in a gymnasium, makes new acquaintances, and learns to live in a new environment. Ludwik makes a friend: Marek, a high school student who participated in the Warsaw Uprising. Marek's father is imprisoned by the security services on charges of spying for American intelligence. As a result, in 1947, Marek founds an underground organization to fight communism.