During her impoverished childhood, Gyeo-wool suffered from asthma and lung problems due to a fire accident, and her family struggled after her stepmother's business failed. Nevertheless, her reliable stepbrother, stepmother, and father were precious family members and pillars of support for her. So, she joined Daejung Group after graduating to take responsibility for her father's money issues and her brother's tuition fees and acted as the breadwinner of her family. Even after getting married, she was able to do so because she became the daughter-in-law of Daejung Group, which sounds like a Cinderella story that everyone would envy. However, the reality was miserable. Her husband, Yu-jin, suddenly changed his attitude after their honeymoon, and Yu-jin's family began to ignore her. The only person who held her hand was Yu-jin's grandfather Man-joong, who cared Gyeo-wool more than her own children and grandchildren and supported her marriage to Yu-jin. Thanks to Man-joong, Gyeol-wool was able to endure the difficult situation.

One day, as Man-joong suggested, Gyeo-wool and Yu-jin went on a trip to celebrate Gyeo-wool’s birthday. Gyeo-wool wanted to spend a nice vacation with her husband, however, somehow, she couldn't stay awake and fell asleep. While Gyeo-wool was falling asleep, her husband and her friend, Ae-ra were tossing and turning on the bed, while she was asleep. The truth is that Gyeo-wool fell asleep due to medication mixed with her asthma medicine, which Ae-ra gave to her. Ae-ra had been manipulating Gyeo-wool, giving her a tea that had contraceptive and sleep-inducing effects to prevent pregnancy and control her. Due to that medicine, Gyeo-wool, one day, caused a drowsy driving accident, resulting in her losing her sight. Furthermore, Gyeo-wool became pregnant with Yu-jin's child, and, at the same time, Hyun-tae, Gyeo-wool's father, tried to reveal that the accident was caused by Yu-jin and Ae-ra.

Ae-ra, who was cornered, framed Hyun-tae for murder and took Gyeo-wool's daughter away while making Gyeo-wool the daughter of a murderer. At the same time, Hyun-tae had swallowed an SD card with a recording file to reveal the truth about Yu-jin and Ae-ra, and then committed suicide. As Gyeo-wool received Hyun-tae's corneas and learned the whole truth that Hyun-tae tried to tell her. She managed to obtain the evidence her father left behind. However, because of Yu-jin and Ae-ra, she fell off a cliff and suffered from ‘Locked-in syndrome’(*a condition in which a patient is aware but cannot move or communicate verbally due to complete paralysis of nearly all voluntary muscles in the body except for vertical eye movements and blinking). She wanted to take revenge right away on Yu-jin and Ae-ra but her body couldn't move. If only she could move, she would even sell her soul. She screamed in her heart like that.

Did God grant her wish? As if answering her prayers, Gyeo-wool’s is switched with that of an heiress, Se-rin, who has everything unlike herself. Grateful for the opportunity to seek revenge, Gyeo-wool spends four years preparing to take revenge on Yu-jin and Se-ra. She takes Ae-ra's position as team leader, seduces her ex-husband Yu-jin, and tears the two apart. In the process, she begins to develop feelings for Taeyang, the man whom Se-rin had a crush on, and everything becomes even more complicated with revenge against Ae-ra and Yu-jin, her relationship with Tae-yang, and the missing child. To make matters worse, the real Se-rin, who had been trapped inside Gyeo-wool's body, wakes up in four years! Will Gyeo-wool be able to complete her revenge amidst all this confusion?




Oh Se-rin(Cast. Choi Yun-young)
Born into a wealthy family, but losing her parents, Se-rin grew up as a rough and tumble person despite inheriting a vast fortune. With her overflowing wealth, she could have anything she wanted easily, except for Tae-yang, the son of her housekeeper. Tae-yang was always by her side, sometimes like an older brother and other times like a teacher, guiding her through life. Gyeo-wool realized that she couldn't live without him and mustered up the courage to confess her feelings, but his answer was a rejection. He already had someone he loved, even giving up his dreams and life for her. Losing her senses, Se-rin tried to kill herself...
When she woke up, four years had passed, and she found herself in the body of Gyeo-wool, the daughter of the murderer who killed her older sister. Gyeo-wool had taken over her body. She came face to face with Gyeo-wool, who was now in her body and was kissing Tae-yang with her face. Unable to forgive Gyeo-wool for taking everything away from her, Se-rin joins forces with Ae-ra to seek revenge.



Ju Ae-ra(Cast. Lee Chae-young)
Her only goal in life is to become the daughter-in-law of Daejung Group for revenge. Her real name is Kim Hyun-jung, and she even lied about her real age. Thirty-two years ago, her wealthy family collapsed after her father died, and she was sent to various foster homes along with her four-year-old sister, whom she lost contact with. After being adopted overseas and later abandoned, she finally met her uncle, who attempted to exploit her for money but inadvertently revealed the truth about her father's death. Her father had been displaced in surgery due to the intervention of the eldest son of the Man-joog family, and her sister, who had been sent to a foster home, had also died. Ae-ra decides to enter the Daejung family and seek revenge against Man-joong, who had ruined her family and her life. She removes anyone who stands in her way for revenge, including Gyeowool.
Four years later, when Ae-ra tries to stop Gyeo-wool, who has taken over Se-rin's body, she learns a shocking truth.



Jung Gyeo-wool(Cast. Shin Go-eun)
Despite her poor financial situation, she remained positive and optimistic. However, she gradually became exhausted, mainly because of her husband and his family. After their honeymoon, her husband's attitude suddenly changed, and her husband's family began to ignore her. She could endure it because the chairman of Daejung Group and her father-in-law, Man-joong, favored her. However, she did not know that her friend, Ae-ra, and her husband were having an affair. Ae-ra had switched her respiratory medication with birth control pills and had given her a drugged tea, manipulating her to spend secret time with her husband, Yu-jin. But something unexpected happened. Gyeo-wool, who had drunk the drugged tea, lost her vision in a drowsy driving accident. Moreover, when Ae-ra found out that Gyeo-wool was pregnant, she falsely accused Gyeo-wool's father of murder. Gyeo-wool, who lost everything due to Ae-ra and her husband, cried out for revenge, and when she regained consciousness, she found that her soul had switched with Se-rin.



Seo Tae-yang(Cast. Lee Seon-ho)
He was born as an only son to an unmarried mother, but grew up smart and upright, becoming a perfect son and man. However, his life changed when he met Ae-ra. While working part-time to pay for his tuition, he met Ae-ra, who worked as a hostess at a bar and gradually fell in love with her while taking care of her. One day, while trying to save Ae-ra, he accidentally committed a crime and Ae-ra disappeared like a fugitive, leaving him with a criminal record and ruining his dreams and life. He then worked hard as a delivery man to make a living.
In the meantime, Se-rin, who was like a younger sister to him, was turned down by Tae-yang and attempted to kill herself. Amid his agony, he reunited with Ae-ra, but when he saw her abandoning her newborn baby, he thought it was her child and took the baby. And after four years, when he met Se-rin who had returned from studying abroad, he felt a strange sense of familiarity and attraction toward her.

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