Trigger of Murder
Chungsik Chung meets Honam Choi, a friend from elementary school, at a military recruit training center. Honam was short and weak, but had a genius for making trouble--showing his friends how to make a 10-won coin the same thickness as a 100-won coin to use in a video arcade, and how to open a car door to steal a wallet. In middle school, he used to artfully prod kids into fighting or teach his aggressive friends how to make money by collecting protection fees from other kids. Since then, Honam hasn't changed a bit. At the military recruit training center, Chungsik helps Honam smuggle snacks and cigarettes and sell them to other recruits at a higher price. They get caught, but only Chungsik is held responsible and Honam escapes any consequences. Assigned to the same unit later, they begin their military life together. They go through a difficult time as privates, but one day, Honam finally reveals his true colors.
Blue Falcon
Sonam Sim, the main character, enlists as a conscripted police officer in Seokju to escape the abuse of his stepfather who was a shaman. Timid with eyes darting around nervously, he is labeled from the start as a blue falcon, and even his subordinates look down on him. Sinyeok Yu, a second-generation chaebol and celebrity who is placed as Sonam's subordinate, disobeys and beats Sonam when they're alone. Sonam doesn't understand why everyone is ignoring and harassing him when he hasn't done anything wrong.
Because of a tip-off about Sonam and Sinyeok, the second platoon where they belong receives special corrective training, and Sonam collapses during an arduous drill. Worried about complaints, the commander gives Sonam a special vacation. The three villainous senior officers, who dislike Sonam and happened to be outside at the time of the incident, are angry for getting into trouble because of him and decide to punish him when he returns from vacation.
When the Uninvited Arrive
About to get married, Jongwoon Park contacts his comrades who served in the military with him and informs them of his wedding. A long time has passed since their time in the military, but his former subordinates treat him the same way as when he was their superior. Jongwoon, his fiancée, and his former subordinates are laughing together, chatting about their military life, when someone mentions Malyoung Son, who was discharged due to a family situation, making everyone uncomfortable.
Then Malyoung, uninvited, appears. Almost unrecognizable, he no longer looks kind or gentle. Tattoos covering his arms and eyes ferocious, he shakes hands with Jongwoon, scratching his bushy beard. Though uninvited, he keeps uttering risky jokes, and then, other comrades also start bringing up the ugly things Jongwoon had done in the military.
The Missing Notebook
Sangjin Lee, a private listed as a conscript requiring special attention, one day, executes the task that's been on his mind. While on duty, he enters the barracks fully armed with grenades and firearms, and kills more than twenty soldiers. He attempts suicide, unsuccessfully, and is hospitalized with fatal injuries. It was certain who did it, but the motive was unclear.
Sergeant Mingyu Kang, knowing that the military will close the case by just pinning the blame solely on the shooter Sangjin, decides to dig up the whole story. He discovers that Sangjin doesn't have a military notebook that a private must carry.