Episodes 01
In 2004, 17-year-old high school student Moon Dong-eun is ruthlessly bullied by a group of her rich peers, led by Park Yeon-jin and including Jeon Jae-joon, Choi Hye-jeong, Lee Sa-ra and Son Myeong-oh. Dong-eun files a police report but Yeon-jin’s mother uses her connections to cover up the incident. Dong-eun’s homeroom teacher, Kim Jong-moon, dismisses her allegations and blames her. The group punishes Dong-eun by burning her body with a hair iron, and allowing Myeong-oh to sexually assault her. Dong-eun applies to drop out of school, listing the group as the reason. Jong-moon beats her in front of other teachers for “lying”. Yeon-jin’s mother bribes Dong-eun’s mother to change the reason on the form to “maladjustment”. After taking the money, Dong-eun’s mother abandons her. Before moving away, Dong-eun returns to the school and vows to the group that “they’ll meet again”. Over the next few years, Dong-eun earns a GED and enrolls into university to study education. In 2022, an adult Dong-eun watches Yeon-jin, now a weather presenter, on television in her apartment, surrounded by photographs of those who have wronged her.
Episodes 02
While studying, Dong-eun begins gathering information on the group. Jae-joon inherits a country club and boutique and has a fling with Yeon-jin; Hye-jeong becomes a flight attendant and has unrequited feelings for Jae-joon; Sa-ra becomes an artist hooked on drugs; Myeong-oh becomes Jae-joon’s lackey and Sa-ra’s drug dealer. Dong-eun works as a tutor and meets Joo Yeo-jeong, a medical intern who shows interest in her and teaches her the game Go. Yeon-jin marries Ha Do-yeong, the CEO of a large construction company, and has a daughter, Ha Ye-sol. Dong-eun qualifies as a teacher, then abruptly leaves without telling Yeo-jeong. Dong-eun goes to the boutique, where she tells Myeong-oh that she has information he can use to make money. Dong-eun leases an apartment in Semyeong overlooking Yeon-jin’s house. One night, while searching the bins at the house of Semyeong Foundation’s chairman, Dong-eun is confronted by the housekeeper, Kang Hyeon-nam. Hyeon-nam offers to help Dong-eun if she kills her abusive husband.
Episodes 03
Dong-eun hires Hyeon-nam to gather information on the group, while also tutoring Hyeon-nam’s daughter on the weekends. Dong-eun realizes that Ye-sol is colorblind, a trait shared by Jae-joon. Dong-eun plays Go at a club, where her skill intrigues Do-yeong. Dong-eun encounters Yeo-jeong, now a plastic surgeon, on a train; he confesses that she helped him through a dark time before they part ways again. Dong-eun tells Myeong-oh that she knows who pushed Yoon So-hee, a student bullied by the group before they targeted Dong-eun, to her death. Dong-eun offers to give that information to Myeong-oh in exchange for his help; he gives Dong-eun Jae-joon’s hair samples. Yeon-jin, Jae-joon, Hye-jeong and Sa-ra gather at the school for an alumni awards ceremony; Dong-eun introduces herself. Dong-eun uses information gathered by Hyeon-nam to blackmail the chairman of Semyeong school district for a transfer to the elementary school attended by Ye-sol.
Episodes 04
Dong-eun has a heated exchange with Yeon-jin and Jae-joon. Jae-joon orders Myeong-oh to find out Dong-eun’s plans. On his father’s death anniversary, Yeo-jeong receives a letter opener that belonged to his father from his mother, Sang-im, who is also the director of the hospital he works in. Yeon-jin learns from Ye-sol that her new homeroom teacher is Dong-eun. Yeon-jin goes to the school to tell Dong-eun to stay away from her daughter, but Dong-eun replies that she intends to make Yeon-jin suffer. Yeon-jin learns that Jong-moon has died. Dong-eun told Soo-han, Jong-moon’s son and Dong-eun’s senior at university, that she intends to expose Jong-moon’s treatment of her to the education department. Soo-han killed his father by triggering his asthma and denying him help, so as not to jeopardize his own career prospects. Dong-eun receives information about So-hee from the ex-school nurse. Myeong-oh gives information about Sa-ra’s drug habit and Hye-jeong’s partner to Dong-eun. She points him to the mortuary, which he discovers to be the location of So-hee’s body, her parents having refused to claim it as they dispute the police’s ruling of suicide. Dong-eun continues to play Do-yeong at the Go club.
Episodes 05
Do-yeong gives his card to Dong-eun. Yeon-jin does some digging of her own about Dong-eun at the school. Dong-eun reveals to Yeon-jin that she knows about Ye-sol’s color blindness. Jae-joon receives an envelope containing Ye-sol’s toothbrush. Yeon-jin floats the idea of sending Ye-sol to school abroad to Do-yeong, but he is unconvinced. Yeon-jin hires her mother’s police friend to gather information on Dong-eun. Hyeon-nam steals Hye-jeong’s phone and gives it to Dong-eun. Dong-eun blackmails Sa-ra with her drug habit for a bag full of cash. Dong-eun contacts Yeo-jeong after years of silence, and apologizes for her treatment of him. Yeo-jeong asks Dong-eun if she’ll ever date him, to her amusement. Dong-eun replies that she does not need a prince, but an “executioner”. Dong-eun tells Myeong-oh who she believes pushed So-hee. Myeong-oh contacts the rest of the group and Do-yeong. Myeong-oh plans a trip overseas, but is attacked by an unknown person.
Episodes 06
Yeo-jeong resigns from the hospital to open a practice in Semyeong. Hyeon-nam tells Dong-eun that Myeong-oh is missing. Dong-eun discovers that Myeong-oh bought a one-way plane ticket but did not use it. While driving at night, Dong-eun receives a warning from Hyeon-nam that she is being followed. Dong-eun leads them on a chase which ends in a collision and an exchange of phone numbers. Suspicious, Dong-eun asks Hyeon-nam why she was following her. They both realize they could easily betray the other. Hyeon-nam tells Dong-eun of a simple dream of a slow dinner with her daughter. Do-yeong receives a photograph of him with Dong-eun. The group and Do-yeong try to reach Myeong-oh unsuccessfully. Do-yeong meets Jae-joon; they realize both of them received strange packages. While getting her car fixed at a mechanic’s, the sound of workers barbecuing meat triggers a flashback and sends Dong-eun into a panic attack. Jae-joon discovers that Ye-sol is his daughter. Hye-jeong receives an envelope full of private images from her phone. Dong-eun tells Yeo-jeong of her plan for revenge. When he tries to discourage her, she shows him the extensive scarring on her body. Yeo-jeong offers to be her “executioner”.
Episodes 07
Yeo-jeong admits to Dong-eun that he has anger of his own. Do-yeong grows suspicious of the behavior of the group, particularly between Yeon-jin and Jae-joon. Sang-im receives a letter intended for Yeo-jeong from Kang Yeong-cheon, the murderer of her husband and Yeo-jeong’s father. Yeo-jeong fantasizes about killing Yeong-cheon. Dong-eun devises a plan to use the money from Sa-ra to send Hyeon-nam’s daughter to study in the US. Do-yeong learns from Ye-sol that her teacher and Yeon-jin know each other from school. Hye-jeong and Sa-ra search for Myeong-oh in his apartment, finding his plane ticket and passport. Jae-joon makes plans to take back Ye-sol, which will require a divorce between Yeon-jin and Do-yeong. Dong-eun reveals to Hyeon-nam that on the day So-hee died, she had Yeon-jin’s name tag in her hand; she intended for Myeong-oh to blackmail Yeon-jin, but his disappearance complicates matters. Dong-eun bumps into Hye-jeong at a temple. Jae-joon confronts Yeon-jin with Ye-sol’s paternity; they fight, then kiss. Do-yeong attends one of Ye-sol’s classes and sees Jae-Joon. Do-yeong realizes that Ye-sol’s teacher is the same Dong-eun that went to school with Yeon-jin and Jae-joon, as well as the Go player he played with.
Episodes 08
Dong-eun makes Hye-jeong report Myeong-oh’s disappearance to the police. Jae-Joon hints about Ye-sol’s paternity to Do-yeong. Dong-eun tells Jae-Joon that if he wants to claim Ye-sol, his best ally is her, not Yeon-jin. Do-yeong learns from Hye-jeong that Yeon-jin heavily bullied Dong-eun and others. Yeo-jeong plays Go with Do-yeong, then reports to Dong-eun. Do-yeong asks Yeon-jin about her history with Dong-eun, but she urges him to forget about the past. Jae-Joon asks Yeon-jin to divorce Do-yeong so that he can marry her and claim Ye-sol, but Yeon-jin replies that she still loves Do-yeong. After finding little to pressure Dong-eun with, Yeon-jin switches to Dong-eun’s mother. Yeo-jeong asks Dong-eun about an unknown woman on her wall; she replies that it is her mother. Sang-im visits Yeong-cheon in prison, who confesses that he sent letters to Yeo-jeong to torment him. Dong-eun tells Hyeon-nam that before she proceed with her plans, she intends to send Hyeon-nam’s daughter abroad for her safety. She offers Hyeon-nam out if she wishes. Do-yeong asks Dong-eun for her side of the story. Yeon-jin breaks into Dong-eun’s apartment and sees her wall of photographs, then comes face-to-face with Do-yeong. Yeo-jeong discovers that So-hee’s body is not in the mortuary.