Unforgivable

Original title: 비밀

In the middle of the night, a horrendous murder takes place in a public washroom. Major Crimes detective Dong-geun finds a crumpled up note inside the victim’s mouth. The note contains a date from 11 years ago, and as he digs deeper into the note, he finds out that the victim was a bully in the military, and Dong-geun gets a chance to reflect on his own unsavory past that he has forgotten until now.