Kim Jongin is a lucky man. He's got a girlfriend who adores him, a nice house, and a cushy new job as a special forces detective. 

But there's something that has been eating Jongin away for the past 10 years: the disappearance of his childhood best friend, Do Kyungsoo. 

Now that he's a detective, he's determined to reopen the cold case of his friend's disappearance and find out exactly what happened ten years ago.