15-year-old Prussian princess Sophia Frederica arrives in Russia to marry the heir to the Russian throne Peter III. Marriage does not bring happiness: her husband hates her. But Empress Elizabeth Petrovna needs an heir capable of ruling a huge country, since the capricious and unbalanced Peter is not suitable for the role of the Russian Emperor. After seven years of painful marriage, Catherine gives birth to a son. But the current empress takes little Pavel for upbringing. Separated from her child and deprived of the only chance for female happiness, Ekaterina intends to fight. She is looking for allies among those who do not want to see Peter on the throne...