Watch StreamingCommunity. The woman who will become Catherine the Great marries into the Russian royal family when she weds Grand Duke Peter, the nephew of Empress Elizabeth. Although the couple has moments of contentment, Peter's cruel and erratic behavior causes a rift between him and Catherine. Mere months after Peter succeeds his aunt as the ruler of Russia, a revolt is brewing, and Catherine is poised to ascend to the throne as the country's new empress.