1758. The seven-year war unfolded in full force. The Russians relatively easily captured East Prussia, inflicting a series of defeats on Emperor Frederick. The headquarters of the army under the command of the favorite of Elizabeth Petrovna, Prince Karl of Saxony, moved to the captured Königsberg. In Königsberg itself, the agents of the Secret Chancellery, led by adviser Lyadashchev, started a risky game against the English resident Sakromozo, deciding to use Princess Repninskaya, who was unjustly accused of trying to poison the empress. Prince Nikita Olenev, appointed guardian of Repninskaya, starts a search pass and involuntarily becomes involved in the intelligence struggle. And, of course, loyal midshipmen friends come to his aid - captain Alexander Belov and captain Alexei Korsak.