Peaceful unification between North and South Korea is about to take place. Therefore, the DMZ area near Panmunjom (JSA) will be designated as a Special Peaceful Zone (a.k.a SPZ) for unification of the Korean Commonwealth. So, Panmunjom has entered a overall development phase. However, murder takes place in the DMZ. The suspect is a deserter who is only known as code-name Firefox, the special agent of North Korea.

Dong-hyun is a high school student. One day, he falls from the rooftop and bumps into Pan-soo who is a passerby. Pan-soo is a member of a criminal organization. When the two men wake up in the hospital, they discover that they have switched bodies.

Singing and dreaming together, a talented singer-songwriter and a same-aged keyboardist add harmony and love to each other's lives.