A knight Estelle, called Ishtar of Ersha, is killed by a poisoned knife due to an abrupt betrayal by her lieutenant Khalid. After 3 years, when she opened her eyes, she realized she had become a noble lady, Lucifela in the enemy country, Jansgar. Compared to Estelle, Lucifela’s body is weak and lacks swordsmanship. Her reputation in the world is not good because she has thrown herself into the palace lake to gain love from the crown prince. Meanwhile, when she realizes that her fiancé is a knight of the enemy country, Zed, she quarrels with him thinking of breaking off her engagement.
One day, serial murders only aiming women occur in Jansgar. The rumor runs that a murderer called ‘Swordman’ is Liam, a member of ‘The Knights of Sitora’, and Lucifela escapes from home to investigate the case. However, unfortunately, she confronts the murderer and barely suppresses the murderer with her wit. Zed receives the order from the emperor to capture the murderer and looks at the situation while searching for missing Lucifela, and his negative impression of her changes.
After a serial murder case, while recuperating at home, Lucifela is invited to the imperial palace by invitation from the empress. However, the invitation was caused by Lucifela’s former fiancé, the crown prince and she avenges him who approaches her smuttily. She realizes that her lieutenant, Khalid who has killed her, received dukedom in Jansgar and now lives well in the empire. She tries to throw herself from the balcony with a vengeful mind, but the second crown prince Eozif interrupts her. Lucifela feels despair about her situation which she cannot avenge although she wants to, and kisses Zed with a mind of abandoning herself. Count Aydin misunderstands that she tried to throw herself from the imperial palace again and makes her move to Count’s manor.
Lucifela who moved to the manor realizes that the knights in the manor are in bad condition, so she sells her dress and supports the knight’s armament with that money. While thinking about the reason for the poor condition of the knights, she looks around the manor and realizes that Jansgar is affluent and peaceful unlike Ersha. Looking at Lucifela, who carefully examines the manor, people in the manor begin to think that she has an upright personality different from the rumor.
One day, Lucifela contacts a group of merchants to trade jewels in the Count’s manor. However, the group of merchants was thieves and Lucifela ran away toward the mountain. While running, she confronts Khalid and realizes that all the events were abetted by the crown prince. However, Khalid does not harm Lucifela unexpectedly, protects her from robbers and monsters, and gets wounded. Although she could avenge him by killing him, she did not think that was the proper way of revenge, so she chose to save his life. She passes the crisis with the help of Zed who came to her worrying about her. Zed becomes conscious of Lucifela who shows a different personality from the past and he is attracted to her.
As Lucifela thinks that she needs information to avenge properly, she becomes a friend of Lady Florence of the House of Marquis of Roer. The real Lucifela and Florence had an awkward relationship, but Lucifela whom Estelle entered communicated with her deeply, had a teatime, and took part in a horseback riding contest. In the horse-riding contest, she experiences an accident by someone’s plot, but she overcomes it safely through her horseback riding ability. From this, she gives an impression of “Ishtar” to people around her. Through this, the second crown prince Eozif thinks that the image of Lucifela and Estelle looks similar and begins to examine Estelle.
Through several events, Zed feels a deep love for Lucifela. However, he thinks that if Lucifela rejects him, she will cut the relationship with him like the case of the crown prince, so he cannot confide his mind. At the same time, Khalid hangs around Lucifela. Eozif who thinks that Lucifela is related to Estele, speaks his mind that he is seeking the imperial throne, and suggests she help him on condition of independence of Ersha. Even though it was Ersha’s liberation that she hoped for in her previous life, she is confused that she cannot accept it gladly, and feels emptiness because Zed must leave the capital due to a problem of manor.
While Zed has left the capital, Khalid opens a party, invites Lucifela, and reveals her identity with a trick. Khalid has kept the dead Estelle’s skull and hair and confides that he killed her because he loved her. He says that Ersha was not a good country as Estelle thought and bad things would happen to Estelle after defeat, so he killed her. However, Lucifela cannot forgive Khalid. Although Lucifela wants to avoid Khalid after that, Khalid keeps visiting Aydin’s house and dedicates a bouquet to Lucifela.
Zed returns after solving the problem in the manor and dedicates a broach to Lucifela in the deer hunting contest. However, Lucifela does not attach the broach, and Zed feels disappointed. However, after hearing the news that Zed got hurt in the deer hunting contest, Lucifela climbs up the mountain riding a horse and realizes that she worries about Zed, and at the same time, loves him. She also realizes that the reason for rejecting Eozif’s suggestion is his fear of using Zed’s emotion rather than the independence of Ersha.
Lucifela goes to the imperial palace to see Zed and participates in the empress’ teatime. However, Temir breaks into there and insults Lucifela. Seeing that sight, Zed stands against Temir. At Lucifela’s question of why he did such a thing, Zed confides his heart that she loves her. At first, Lucifela refuses to accept Zed’s confession. However, to avoid Khalid’s continuous visits to the house of Count Aydin and to directly see Ersha’s current situation, she decides to accompany Zed’s mission under the emperor's order.
Three years after Estelle’s death, Ersha has become a more peaceful and affluent country than in the past. In there, Lucifela realizes the truth that Ersha dynasty was corrupted in the past, and the war broke out because the royal family in Ersha abused the empress from Jansgar. Lucifera falls into despair from that fact but feels saved by Zed’s words that although Estelle was used and betrayed, she was an honorable knight who defended her country only with a sword and he pays homage to her. After that, she accepts Zed’s confession, and the two love each other. Lucifela clears the relationship with the Knights of Sitora including Khalid in Ersha and plans to marry Zed returning to Jansgar
However, the news awaiting her was the fact that Count Aydin had been murdered. Moreover, Khalid who could not give up Estelle invalidates the engagement of Zed and Lucifela by using his position as a representative of the house of Count designated by Count Aydin beforehand. Zed resolves civil war for Lucifela, but to prevent Zed from being a traitor, she enters the imperial palace and declares that she will succeed the house of Count Aydin. In front of nobles raising objections, the House of the Duke Idris reveals that they are enemies of her parents and requests a battle.
The House of Duke of Idris looked down Lucifela and was careless, but Lucifela prepared thoroughly and won a victory even though the Duke’s combat ability was twice as powerful as hers. Duke Idris is sentenced to death for his defeat and Lucifela is recognized as a Count honorably. Zed who opposed the battle in manor also participated in the war, without Lucifela’s recognition, protected her, and defended her from the assassination of Temir. While guarding Lucifela in the battle of the manor, Zed realizes that Lucifela is Estelle and confides again to Lucifela that he loves her as Estelle. Lucifela is confused as her identity is uncovered, but because her anxiety that Zed might love only Lucifela, not Estelle, has been resolved, she accepts the confession. As a result, the two people become a couple wholly.