A righteous prosecutor, life reset, punish the villain! Kim Hee-wu, a hot-blooded prosecutor, was murdered and thrown into the ocean while pursuing the tyrant who controlled Korea. However, Kim Hee-wu encounters a grim reaper who grants him a second chance, sending him back to the time when he was 18 years old. As a high school student, Kim Hee-wu prepares to punish the tyrant Jo Tae-seop. "To catch the devil, you must become one."