"The Executioner" is a multi-part historical drama set in the mid-1960s. The story follows two detectives who take on a highly curious and convoluted case: they must find and arrest a woman who, during the Great Patriotic War, switched sides to the Germans and cold-bloodedly killed civilians, soldiers, and partisans. According to approximate data, this executioner may have claimed the lives of over a thousand people. The detectives' investigation begins with an unexpected murder in a small inconspicuous village. Someone brutally deals with Petya Yakovlev, a school graduate who had been gathering his grandmother Raisa's former comrades-in-arms, who had distinguished themselves on the front lines, for a long time.