The protagonist of the story, physics teacher Akif Erdem, wants to give his students a "lesson in humanity". But Teacher Akif uses a different method of teaching than the teachers we know and are used to.

For his last lesson, Akif Erdem first takes the 12A class of Küçükkapı High School hostage and uses a bomb to cut the class off from the rest of the school. The children and Akif will no longer be able to go outside... And Teacher Akif asks the children a question; "Who among you caused the death of Rüya Örnek, a student in class 12A?"

There is only one way for the young people who are taken hostage to get out of this situation; telling the truth! In time, the students will understand and love Akif Teacher, who tells the children and even the whole country about the importance of being a "good person" and teaches them to empathize and think; they will realize the mistakes they have made and successfully complete their last lesson.