Sung Jinwoo accompanies his sister Jinah to a parent-teacher meeting, where he is asked to counsel her classmate Han Song-Yi, who aspires to become a Hunter. To expose her to the profession's harsh realities, Jinwoo takes Song-Yi to observe rookie Hunters training at the White Tiger Guild. However, they unexpectedly become trapped in a perilous Red Gate, leading to an advanced dungeon where survival is uncertain.