November 1927. Former white officer Vladimir Saburov secretly crosses the border of the USSR. On the day of the 10th anniversary of the revolution, he must blow up the cruiser Aurora, on board which will be the leaders of the Soviet Union. The Leningrad GPU learns about this, and experienced security officer Daria Skrebtsova receives the task of eliminating the terrorist. But her superiors know nothing about the fact that in 1917 Vladimir and Daria were a couple in love...