The 1930s. Naval maneuvers are underway. On orders from the command, three submarines are to "attack" a battleship. In the heat of the "battle," a fourth periscope appears. Where did the fourth submarine come from? Is it one of ours or an enemy vessel? These questions must be answered immediately by the commander of the destroyer "Otvažny," otherwise...
The positive assessment of the work of young historian Nadezhda Kovrova went to her head. Confident in her infallibility, she makes a mistake.
