Melancholia

With new ambitions for Asung High School, Noh Jung-ah hires Ji Yoon-su to lead an advanced math program. A controversial placement test is administered.

Asung High holds a competition to select a representative for the International Mathematical Olympiad. Yoon-su calls Paik Seung-yoo to detention.

The results do not go according to plan for some. Jung-ah grows uncomfortable with Yoon-su's unwillingness to comply with the school culture.

Threatened by Seung-yoo's rise, a malicious rumor begin to spread. Yoon-su learns the real reason why the IMO Speech Competition is happening.

The success of Asung High's students at IMO attracts attention and controversy. Yoon-su tries to set things right, but finds that she may be too late.

Yoon-su distances herself from Seung-yoo. Sung Ye-lin prepares for midterms as usual, but this time, something doesn't add up.

Years later, Seung-yoo tours the country while giving lectures and interviews as a celebrated mathematician. He meets an attendee with a familiar nickname.

Jung-ah tries to get her daughter to see a reputable but secretive tutor. Seung-yoo invites his students to participate in his newest project.

Seung-yoo offers his help to Yoon-su who's gathering evidence to expose the inner workings of Asung High, but she refuses to have anything to do with him.

A teacher gets arrested. Seung-yoo finds out who spread the rumor four years ago. Choi Si-an finds someone to help her solve a difficult math problem.

To become the director of the Asung Foundation, Jung-ah uses Seung-yoo to her advantage, while Noh Yeon-wu turns an enemy into an ally.

An old scandal surfaces back into the spotlight. Yoon-su worries that Seung-yoo may be jeopardizing his future by confronting the past.

When accusations come in from all sides, Jung-ah fights back. Yoon-su enjoys a relaxing time with Seung-yoo before her final goodbye.

To keep the police from digging any deeper, Jung-ah appoints a fall guy. Si-an finds something suspicious in Kim Ji-na's bag.

While Jung-ah scrambles to contain the secrets and lies, Seung-yoo and Yoon-su urge witnesses to come forward. Asung High's days are numbered.

Knowing that Jung-ah's influence is far-reaching, Yoon-su chooses a different way to expose the truth. Seung-yoo invites a friend to come out of hiding.