The play is set in a parallel world. God releases the devil into the world, and the devil opens the door to the parallel world. If there is a me in another world who lives a better life than me, will you change your life with him? Facing these questions raised by the devil, the science-oriented emperor of the Korean Empire, Lee Gon, who wants to close the door to the parallel world, and the liberal arts-oriented Korean criminal policeman, Jung Tae-eul, who wants to protect his love, interpret a romance that is sometimes exciting, sometimes bitter, and at different levels through cross-world cooperation.