Class of Lies

Mu Hyuk is in charge of defending Kim Han Su, the suspect of the attempted murder. According to the circumstances, Han Su is the only one who has a motive and chance to kill Su Ah. However, Han Su insists that he is not the criminal. Mu Hyuk wants Han Su to give him evidence to believe his assertion, and Han Su says that Su Ah is his girlfriend.

Destroyed and defamed, Gi Mu Hyeok returns as a teacher and infiltrates Cheonmyung High School to uncover the truth behind Jung Su Ah's death. On his way to school for the start of the semester, he sees Ha So Hyun in an embarrassing situation. Meanwhile, the kids at the school plan a bare-knuckle fight on the rooftop of the school.

Late at night, Gi Kang Je and Yu Beom Jin meet for the first time in a strange ordeal dealing with Ahn Byung Ho on the rooftop of Cheonmyung High School. Although they resolve the situation, Beom Jin leaves Kang Je with a little insight into the school. Kang Je starts to notice suspicious things all over the school and gets a little closer to finding out the truth behind the murder. Meanwhile, So Hyun worries over Byung Ho getting bullied in and out of school.

Won Suk tracks down the man from Jung Su Ah's townhouse video. Strangely, it turns out he's a chauffeur hired by the general manager of the school, Lee Tae Sook. Could it be him who is behind it all? Meanwhile, at the school, Jun Jae posts an altered picture of Kang Je and So Hyun in bed together on the school’s secret community portal that starts to spread.

Kang Je finds out who is the secret sysop of Cheonmyung High's Student Community Portal. He tells the secret sysop that the portal should be shut down. Yun Ah shows So Hyun the student community portal, and So Hyun gets to see the photos of Su Ah. Meanwhile, Kang Je gets to know that Su Ah and Han Su were from the same orphanage.

Young Hye wants to kick Jun Jae and Byung Ho out of Cheonmyung High School, but So Hyun thinks it is unfair to Byung Ho. Kang Je gets to know that Jun Jae’s family is having a financial problem. Meanwhile, Kang Je goes to Noeul Orphanage to find out some information related to Han Su and Su Ah.