In a world where humans with special talents known as hunters must fight deadly creatures to save humanity from probable extinction, Sung Jinwoo, a famously weak hunter, finds himself in an apparently never-ending battle for survival. A mysterious program known as the System selects him as its lone player one day after he barely survives an incredibly strong double dungeon that almost wipes out his entire party. In exchange, the System grants him the incredibly rare ability to level up in strength and turn anyone he kills into a devoted minion known as a shadow. Jinwoo then embarks on a quest to learn the truth about the origins of his talents and the mysteries of the dungeons, facing out against a variety of human and monster foes.