凯瑟琳去俄国嫁给皇帝。当上皇后后，她意识到彼得是个自私的孩子。直到她的仆人玛丽亚尔建议他们推翻他，她才感到绝望。

凯瑟琳朝着政变迈出了第一步。她听从玛丽亚尔的建议，试图勾引并招募宫廷知识分子奥洛伯爵。这是一场灾难，但他最终相信了。

凯瑟琳，奥洛和玛丽亚尔继续他们的政变计划。彼得注意到凯瑟琳的不快，给了凯瑟琳一个不育的情人，利奥。她起初犹豫不决，但利奥设法吸引了她。

凯瑟琳试图管理自己在法庭上的声誉和她与利奥的关系。教会一位有影响力的族长去世了。奥洛试图影响彼得的换人决定。

随着与瑞典的战争继续激烈，凯瑟琳和伊丽莎白阿姨访问了俄罗斯前线的军队。格里戈挣扎着与彼得和乔治娜的关系，毒死了彼得。

在经历了濒死的经历后，彼得现在对凯瑟琳的进步思想持开放态度，并希望专注于继承人。奥洛试图找出是谁毒死了彼得并面对着自己的恶魔。

凯瑟琳很乐观，直到天花爆发，彼得又恢复了原来的生活方式。与此同时，利奥和凯瑟琳的关系受到影响，乔治娜想念彼得。

凯瑟琳有机会出国旅行时，她的政治能力受到考验。利奥想离开法庭。玛丽亚尔把政变的事告诉他，试图让他留在那里。

一具尸体被发现了。彼得决定折磨宫殿里的每一个人，找出那些凶残的叛徒。玛丽亚尔向阿奇透露凯瑟琳的计划。凯瑟琳有一个改变人生的启示。

凯瑟琳继续发动政变。玛丽亚尔泄露了一个秘密，背叛了她。凯瑟琳意识到，一个伟大的俄罗斯的唯一机会就是战斗，不管牺牲多少。

主要讲述俄罗斯帝国女皇凯瑟琳大帝的崛起以及她与丈夫彼得三世之间的激烈冲突，描绘了年轻时的凯瑟琳以及与彼得三世皇帝的婚姻，以及谋权篡位的过程。第二季中，凯瑟琳怀孕了，但她和彼得三世的王座之争仍在继续，她不仅会成为母亲，还将登上俄国皇位

Catherine, Orlo and Velementov begin their rule of Russia and unexpected obstacles appear. Peter is on a journey of self-improvement under house arrest but convinces Catherine to let him attend her coronation and hand over his crown.

Catherine’s grief over the loss of Leo during the coup finally catches up with her. Peter’s part in Leo’s death, and the discovery that he just murdered a noble, causes Catherine to lock Peter in his apartments with only his mummified mother for company.

The Ottoman Ambassador pays Catherine a visit as tensions between the regions run high. But Peter fights to win his allegiance and prove to the court he is more fun than Catherine, in an attempt to destabilize her by throwing a baby shower.

A crocodile roams the court, and Archie sends everyone into uproar by suggesting it might be an omen against Catherine’s leadership.

Catherine is frustrated by the lack of meaningful change in her rule of Russia so far. Seeking to shake the court out of its complacency, she plays a joke on them involving a serf to prove a point, but it gets wildly out of hand with tragic consequences.

Catherine’s team is falling apart and she begins doubting her reign when her mother comes to visit. She works hard to hide the realities of the court from her mother and puts on a science fair for which Russia must come up with the best invention.

Elizabeth pronounces that Catherine’s baby will be born in 7 days and the court begins preparations involving rituals for Peter and Catherine. Conflict with the Ottomans heightens, and Catherine tries to run the country while on forced bed rest.

Catherine and Peter are co-parenting their newborn son, Paul, with the help of Elizabeth and trying to avoid their feelings for each other. When Paul goes missing, Peter and Catherine are driven together in their quest to find him.

Catherine makes a devastating discovery about Peter before traveling to the war front for a meeting with the Sultan. Peter considers his options now Catherine knows his secret and all parties come together for a final showdown at Marial’s wedding.

Catherine and Peter seek some marriage guidance after the chaotic events of the previous day left them in an awkward place in their relationship.

Catherine is visited by the UK and US Ambassadors both wanting her to intervene in the War of Independence. Maxim takes issue with the public displays of affection between Grigor and Marial.

Catherine involves the peasants, nobles and merchants in a conference designed to bring change to Russia. Peter’s hunt for revenge on an historic enemy threatens to destabilise Catherine’s attempt to outlaw murder.

Arkady and Tatyana help Peter and Catherine through a rough patch as they clash over their son Paul. Catherine fears Paul will grow up to be a ruthless and careless leader and Archie and Elizabeth are alarmed when Catherine refuses to ordain him.

Peter is once again tormented by his father, Peter the Great’s expectations and his failure to continue the legacy of his empire. Catherine must decide what to do about the unrest being stirred up in the regions, but Velementov is in no state to help her.

Catherine tries to persuade Peter to come home whilst Hugo re-doubles his attempts to regain his kingdom. Georgina continues to play her complicated court games.

Catherine wants to bring more fun to the court. With Georgina’s help she stages a festival of truth, jokes and stunningly clever ideas. Katya puts on a play that challenges Catherine’s reign, and Catherine samples Peter’s invention of salty desserts.

Catherine introduces divorce to the court with unforeseen consequences. Grigor befriends Maxim and goes stag hunting, and Elizabeth and Petrov go on a trip to the regions.

Under orders from Catherine, Grigor hides out in the forest with Paul. Catherine plays a dangerous game with herself to prove that her destiny lies in Russia, and grapples with the impact Peter’s decisions have on her rule.

Catherine meets court scientist Nikolai, who announces a comet is about to pass through Russia. She uses this phenomenon to her advantage and in the face of some huge challenges, unearths a new side of her leadership.