In a world where dungeons have emerged and certain individuals become hunters, South Korea presents a unique opportunity—become a hunter and serve for a decade, and your siblings will be excused from military duty. This has resulted in an odd trend where affluent families adopt children to protect their own. Yeon-woo was taken in under these circumstances, becoming a hunter to safeguard his younger brother, Jeong-woo. Now, after five years of service, when an unfamiliar dungeon appears close to Jeong-woo's university, Yeon-woo steps forward for a perilous mission, prepared to risk everything to defend his brother—even his own life.