所有分集

刚刚离婚的韩国大学教授都敏宇，应亨俊的请求，收留了亨俊的儿子允浩。亨俊曾对都敏宇怀有特殊的感情。允浩住在都敏宇家后，行为举止越来越大胆，这让都敏宇开始动摇。而禁止师生恋的“第101条”也成为了两人之间的障碍。

与允浩意外接吻后，珉宇试图保持师生关系的界限，但允浩却主动接近他。与此同时，随着校园内不正当关系的真相逐渐浮出水面，一股疑云开始笼罩这所看似平静的校园。

Upon entering Min-woo's lab, Yoon-ho runs into Park Seung-heon, who harbors special feelings for Min-woo. However, as Seung-heon suddenly disappears and a series of alarming signs follow, it becomes clear that Yoon-ho has another motive for staying by Min-woo's side: to uncover the truth behind his brother's death.

Seung-heon confides in Yoon-ho about his past relationship with Min-woo and the fact that Chi-won disappeared shortly afterward. Yoon-ho, who had suspected his brother was missing, confronts Min-woo about the truth. Upon hearing that Chi-won had committed suicide, he decides to believe him, but when it is revealed that Chi-won is actually alive, it foreshadows yet another secret.