A successful lawyer, Moo-hyeok, is appointed as the legal representative of Kim Han-soo, a high school student facing charges of attempted murder and possible manslaughter; evidence indicates a strong case; however, Han-soo denies all involvement.

A defamed Moo-hyeok seeks the truth of Su-a's death and goes undercover as a temporary teacher to find the truth; the term resumes and, on the way to school, teacher Ha So-hyeon walks into an awkward situation.

Late at night, Kang-jae and Beom-jin meet up at the rooftop of the school with matters about Byeong-ho; Kang-jae takes a look around the school and notices areas of suspicion and gets a little closer to revealing the truth behind the murder.

Won-seok realizes the man in Su-a's townhouse video is a hired driver of Cheon Myeong High School's administrator; a strange photo of Kang-jae and So-hyeon surfaces on Cheon Myeong High School's community portal.

Kang-jae declares the administrator of the online portal must be found and Cheon Myeong High School's private community should be shut down; Kang-jae's real identity is at risk of being revealed.

The four friends of Cheon Myeong High School become edgy at the mention of Su-a's murder and surprising aspects of their personalities are slowly exposed; So-hyeon becomes aware of Kang-jae's real identity and stops him.