In the apocalyptic era of rampaging skeleton beasts, Luo Chen awakens the seemingly useless F-grade librarian profession, but actually holds lost combat secret classics, and can transform into a flame swordsman to protect the city. While working as an ordinary library administrator, he secretly fights against skeleton beasts and evil alien forces. During the cruel graduation trial, Luo Chen upholds morality, protects companions, shatters the villains' conspiracy to destroy candidates, and interprets responsibility and national righteousness beneath an ordinary identity.