On the night that 17-year-old Dong-jun's only friend, Kang-hyeon, fell from a high place, Dong-jun made a choice that determined the direction of his entire life. Dong-jun's regrets and remorse following that choice made him experience life in three different universes. These are the various lives of the 42-year-old Dong-juns who live different lives in Seoul, Daegu and Busan 20 tears later.

So Long, See You Tomorrow

An education officer who was dispatched died after a gunshot went off in the dead of night. At the same time, deserters flee to the DMZ in the access control zone, and the 3rd platoon is urgently deployed to the DMZ search operation. There, the crew sees an unidentified soldier, not a deserter or a search crew.