The positive assessment of the work of young historian Nadezhda Kovrova went to her head. Confident in her infallibility, she makes a mistake.

The young officer Sergei Lukonin faced severe trials: the war in Spain, an injury, escape from captivity, and the battles at Khalkhin Gol. Yet, he overcomes all hardships, showing courage and conviction in the justice of the cause he is fighting for.