Yang Yo-han falls into the Abyss, the worst dungeon, due to a friend's betrayal. In the dungeon filled with monsters, Yo-han meets Lee Hyun-muk, an Awakened being considered the strongest in Korea, who disappeared into the Abyss years ago. "Lee Hyun-muk, you can't kill me, you know? I'm a person..." "A person..." "That's right, I'm a person... And Lee Hyun-muk is a person too." However, Lee Hyun-muk is half-insane due to the influence of the Abyss, and Yo-han struggles to survive in the Abyss with Lee Hyun-muk, who occasionally returns to his senses, by treating his wounds and finding food. "This place experiences a phenomenon about every few decades. And I call it 'The Flood'." "The Flood?" "As the Flood approaches, the pollution and madness become more severe... Just like I was a moment ago." However, due to the sudden arrival of the Flood, Lee Hyun-muk goes completely insane... "Why doesn't the sheep cry?" "I'm not a sheep, I'm Yang Yo-han..." "My sheep-sheep." The harsh environment of the Abyss, the festering wound on one leg, Not only the terrifying monsters that wail and attack, but also The bizarre behavior of the insane Lee Hyun-muk.... Thanks to this, Yo-han's otherworld escape story has no day without tears!