When the most popular female student, Jeong Soo-ah gets stabbed in her home, her classmate Kim Han-su got framed for her murder. Gi Moo-hyeok, a shrewd lawyer from prestigious Songha law firm, is assigned to defend Kim Han-soo. To avoid a scandal the school administrators went out of their way to keep the murder under wraps. Gi Moo-hyeok tries to persuade Kim Han-soo to take a plea deal and admit to the murder in exchange for a lighter sentence. But Han-soo refuses. Without Kim Han Soo’s cooperation, Moo-hyeok tries to create reasonable doubt during the trial by suggesting that Jeong Soo-ah is an escort and any of her male clients could have attacked her. This enraged Han-soo who had no choice but to put the blame on himself to protect Soo-ah’s reputation. The case crashed which also saw the end of a Moo-hyeok’s career. To regain his reputation as a lawyer, he goes undercover as a substitute teacher named Gi Kang-jae. There he discovered the online and physical bullying the students in the school are perpetrating. Together with the PE teacher, they team up to uncover a secret society of privileged students who control fellow students and even teachers.
Jang Seon-gyul ( Yoon Kyun-sang ) is the boss of a cleaning company and has Mysophobia and is obsessed with cleanliness. Gil Oh-sol ( Kim Yoo-jung ) is an ordinary girl that is struggling to make ends meet, willing to take on any dirty jobs just to survive. When the two eventually crossed paths, they eventually got pass their differences and fall in love.