The main character is an unassuming art teacher who came to the school two years ago. It is ten days before graduation and the students' high school days are about to come to an end uneventfully--or so it seemed.

The teacher gathers his 29 students and says,

"From this moment, you are my hostages."

A blast rips through the campus and the kids are flustered. In an instant, the teacher-student relationship turns into a criminal-hostage relationship. This is the beginning of their "final class," which is about the truth behind the suicide of their classmate a few months ago. With no suicide note or last words, the school's star student suddenly left this world. One teacher holds 29 students hostage and makes them face the truth about something they all put a lid and turned their backs on. Why did their classmate suddenly commit suicide? Why did the teacher decide to take such a sensational approach to conducting his final class?

A teacher's final class becomes the stage for a chain reaction between the mysterious details surrounding the incident. Depicted within ten days, this time-limited drama series highlights people who are dying to live. A shocking school mystery beyond anyone's expectations! Until the truth is unveiled, nobody can graduate.