Hye-in, a student of Seonwoo Girls' High School, works as a part-timer to make ends meet. One day, she gets a tutoring job for a wealthy middle schooler who wants to go to Cheongdam International High School. While her student is away, Hye-in takes a photo with the student's designer bag, and the photo goes viral.

Hye-in starts posting more pictures taken with Na-yeon's expensive stuff. She goes overboard and even tries on Cheongdam High's uniform. Na-yeon catches her in the uniform and finds the pictures Hye-in's been uploading. Hye-in begs Na-yeon not to tell her mom about it, and Na-yeon makes Hye-in run errands for her instead.

Na-yeon's family makes complaints to Hye-in's school about her forgery and fraud. Hye-in is on the verge of getting expelled, so she meets the school director of Cheongdam High and begs for mercy. There, she witnesses something she shouldn't have.

Hye-in is offered a place in Cheongdam International High School in return for keeping silent about the incident she witnessed. She buys a new pair of shoes for her new school but accidentally loses them. She runs into Je-na, who happened to be wearing the same shoes and mistakes her for a thief.

Hye-in forcefully takes the designer shoes off of Je-na and hurts her without knowing who she is. Je-na is determined to make Hye-in's life miserable at school. Do-eon sees Hye-in's application for enrolment in his father's study and decides to approach her.

Do-eon asks Hye-in to tell him what happened on the night Hae-in fell from the rooftop. But Hye-in sets a condition in exchange for telling the truth. Hye-in gets invited to the sorority party, an exclusive party for the rich. There, she runs into Je-na again.

Je-na teaches Hye-in a lesson by ruining her dress and humiliating her at the party. After finding out what happened to Hye-in, Do-eon warns Je-na to stop bullying her. But Je-na pushes Hye-in further and tells her to drop out.

Si-eun tells Hye-in about Lee Duk-min who lends money to the kids in urgent need of money. Hye-in ends up borrowing money from Duk-min without knowing the consequences it could bring. Meanwhile, Do-eon asks Hye-in to help him one more time...

Je-na confronts Si-eun, telling her to leave Hye-in alone, but Si-eun backs her off with the story of her brother. Hye-in is shocked to find out what Si-eun wanted in the first place, but she doesn't back down and finds a way to make it through.

So-mang catches Si-eun and Hye-in in the secluded restroom. After hearing how Si-eun blackmailed Hye-in, he promises to help her. On the day of Yul-hee and Woo-jin's anniversary, the ugly truth gets revealed. Hye-in witnesses something she shouldn't have again.

After Oh Si Eun's death, Kim Hye In becomes the prime suspect in the murder investigation. At school, her classmates harass her with scorn, labeling her an 'Equal Opportunity loser.' Realizing that she may never be able to change the course of her life, Hye In resolves to fight back.

Je Na goes through daily distress caused by her family. Her father is on the verge of divorce, and Cha Jin Uk, a suitor with a contract marriage in mind, suddenly enters the picture. Meanwhile, facing expulsion, Hye In proposes a deal to Je Na to include her as a member of Diamond 6. Would Je Na accept Hye In’s offer?

With Je Na’s help, Hye In makes it into Diamond 6 and decides to act accordingly. Meanwhile, Hae In regains consciousness in the hospital and returns to Cheongdam International High School, but she appears to have lost her memory. Another new student, Jin Uk becomes the subject of gossip. As the backstories of the main characters gradually come to light, will Hye In be able to make it through school life safely?

Amidst being mistreated and looked down upon for her memory loss, Hae In seems to make up her mind and asks Do Eon to take her as his partner to the party. Meanwhile, Je Na joins the party and reveals her secret in front of everyone. As the main characters make bold moves, what is the secret that Hae In is hiding? And what kind of consequences will it bring?

As relationships twist and allegiances shift, Yul Hui begins reaching out to Je Na’s enemies, determined to bring her down. On Je Na’s side, her once dismissive attitude toward Jin Uk begins to soften and the two form a reluctant yet increasingly cooperative alliance. In a tangled web of betrayal, manipulation, and shifting loyalties, no one can tell who is truly a friend or an enemy.

Hye In interrogates Sa Rang about whether he is actually Black Dog. Ultimately, Sa Rang confesses the truth regarding Oh Si Eun’s cellphone. After hearing Sa Rang’s account, Hye In is convinced that the person who took Si Eun’s phone is the one who pushed Si Eun. Meanwhile, rumours begin to spread about Baek Je Na’s drug abuse.

Framed in a drug scandal orchestrated by Yul Hui, Je Na’s downfall seems imminent, until her allies step in. Meanwhile, Hye In follows a clue tied to a wrist injury and begins to suspect who holds Si Eun’s phone. With everyone hiding their true loyalties and intentions, can Hye In uncover the truth and protect herself before it’s too late?

Tensions escalate as Hye In is forced into submission, becoming Yul Hui's pawn. However, Yul Hui's schemes unravel when her role in a setup against Je Na is exposed, putting her in a desperate position. Meanwhile, a new strategy emerges to take down Diamond 6 members, with plans to leak the truth through Black Dog's channel.

After Hae In's death, the fragile balance between the characters starts to collapse. Yul Hui pressures Hye In to expose Je Na with a lie during her engagement ceremony with Jin Uk, using a video as leverage. As the fateful day approaches, Hye In stands at a crossroads. With everyone watching, Hye In’s next move could change everything. Will she betray and bring Je Na down, or choose the truth?

Despite the risk of revealing herself, Hye In bravely exposes Yul Hui and the web of corruption festering within the school during Je Na's wedding. As her meticulous plan sets off a chain reaction, buried truths begin to surface, drawing everyone deeper into chaos. Loyalties get tested, and tension simmers dangerously close to exploding. Meanwhile, Yul Hui seethes with rage as damning accusations come at her from all sides.