Prussia's King Frederick II sends a vanguard to Petersburg to spy on Katharina’s plans. The philosopher and teacher, Stephan Mervier, is impressed and charmed by Katharina, by her intelligence, her charisma. She promotes progress, education and science, but her rule is absolute, and she asserts her power with extreme severity. Mervier despises Russia's for its backwardness and for the misery of its people. He is not alone. The resistance in the Winter Palace is growing. A close confidante of Katharina fights on the side of the oppressed. Mervier falls in love with the courageous rebel, who is in great danger. Because no one gets to cross the great Empress.