The series is based on the feature film "Brest Fortress". It tells the story of the first battle during the Great Patriotic War. The events take place on June 21, 1941. The main characters are Lieutenant Andrey Kizhevatov, Major Petr Gavrilov, and Commissar Yefim Fomin. There was also a young man named Alexander Akimov from the regimental orchestra. He played the trumpet, secretly smoked, and was deeply in love with a girl named Vera. None of the heroes could even imagine that they would become participants in a historic event.