During the Nazi occupation of Poland, a generation of youth comes of age. Stach and his friends start with spontaneous acts of defiance, which can prove deadly, but have no organized purpose. Then, while at work as an apprentice, Stach learns elementary Marxian economics from a shop steward. When he sees the valiant and beautiful Dorota, a leader of the Youth Underground, he volunteers. He recruits his friends, and they become a cell in the resistance, tasting courage, discipline, and tragedy. In the background lies the potential conflict between the Communists and the partisans, both anti-Nazi, both Polish, and on their own collision course.