At the end 1941 the Gestapo opened the first concentration camp in Yugoslavia - Lager Nis. Political prisoners, hostages, Jews, and sick partisans, caught after the invasion of the German punitive raid, were imprisoned in this camp. The spine of the story is formed by the tragic fate of the Nis family Zari: the fate of young Gajdo whom the Gestapo catch as he tries to escape into liberated territory, and of his father Dusan, a respected chemist. Basing itself on authentic events, the film concentrates on room No.12, also known in the camp is digging massive trenches in which the Germans exterminate people day and night, a getaway is being feverishly prepared in the camp. On the 12th of February of 1942, the inmates of room No.12 made their escape to freedom. It was a mass escape from one of the many concentration camps scattered throughout occupied Europe.