
S01E01 Fermat’s Last Theorem
At Asung High, Yoon Su’s new workplace, she gives a tricky question for students who want to join the math club. While no one in the class got the question right, a correct answer sheet...
Now that he has reunited with Yoon Su, Seung Yoo tries to get close to her again. Noh Jung Ah, who doesn't know that Yoon Su has become an elite instructor at an academy, asks the academy for the guidance of her daughter, Ji Na. Meanwhile, Sung Jae appears in front of Seung Yoo and Yoon Su, who are together.
A sexual scandal between a math teacher and a student in a prestigious high school ended in tragedy. 4 years later they meet again, now as adults, to reveal the corruptions in school and to regain one's reputation as a teacher.