After throwing her husband off the throne, and having his successor jailed, and eventually murdered, Catherine will stop at nothing to keep her position. Even her own son is a threat to her. She refuses to marry the man who helped her, for fear he will share the crown. She is charmed by a new man at court, Grigory Potemkin.
Two years pass and Grigory returns from the Turkish war. He and Catherine start a torrid affair. A madman named Pugachev claims to be the dead Peter III and is gaining support from the peasants. Grigory captures him and brings him back to Catherine to be punished.
Prince Paul's wife and child die in childbirth. Catherine forces him to remarry and it produces a boy. Grigory wants to take Crimea and Catherine does not want a war. Their relationship is becoming strained, so she sends him to the Crimea to negotiate the expansion of Russia. She makes Grigory a Prince to the anger of her son and cabinet ministers. She forces them all to resign and sends her son Paul to Austria on a diplomatic tour. She is cleaning house to make way for her lover.
The Turks declare war and Catherine recalls Alexi Orlov to Council. Zubov is used to spy on her. Grigory is ailing from a virus he caught in Crimea. She tries to keep her grandson Alexander from his parents and grooms him to succeed her. While Grigory is back in Crimea, he dies. Catherine is grief stricken and she dies as well. It is discovered that she married Grigory 10 years ago. Paul succeeds her.