Modern youth Ling Jinchuan transmigrates into a immortal cultivation novel, awakening a plot preview system and learning that he is a tragic major villain destined to be slain by the protagonist Xiao Dingtian to help him prove his Dao. To escape a tragic ending, he resolves to lie flat and avoid opportunities: giving away thousand-year immortal herbs, handing over top-tier spirit beasts for cultivation, and breaking his own legs to avoid the sect's grand tournament. However, because junior sister Liu Ruyan mistakes him for the protagonist's substitute, he is forcibly dragged into conflicts. He mistakenly enters a secret realm, accidentally eats a magic mushroom, and is trapped for a millennium. Unexpectedly absorbing the spiritual energy of the secret realm and fusing it with demonic energy, his cultivation skyrockets. With external spiritual energy depleted and a war between righteousness and evil breaking out, protagonist Xiao Dingtian remains obsessed with romance and unequal to the task. A millennium later, the secret realm opens, and Ling Jinchuan unifies the demon race.