Modern girl Ye Lingyue transmigrates into a book as a righteous sect's Holy Maiden and is bound to a system that can rewind time. To stay alive, she remains in the Demon Realm. At the start, the Demon Venerable Mo Yuan nearly tears out her heart, triggering a time rewind. Unexpectedly, Mo Yuan retains his memories too, plunging them into a farcical battle of mutual control through time resets. Ye Lingyue uses her ability to rewind time to resolve crises and tease the innocent Mo Yuan, gradually winning his heart. Immortal sect elders set a trap, using Ye Lingyue's heart's blood to ambush Mo Yuan and ignite a crisis between the immortal and demon realms. To protect Mo Yuan, Ye Lingyue joins forces with Lin Qiaoqiao, the original heroine, to expose the conspiracy and fight the villains. In the end, they thwart the scheme involving the Heaven-Slaying fragments, restore peace between the immortal and demon realms, and Ye Lingyue gives up returning to her original world, choosing to remain in the Demon Realm with Mo Yuan.