Lin Yan, chief specialist of the Tianshu Bureau, is born with an S-rank lightning ability known as the Purple Firmament Thunder Body. However, he accidentally becomes bound to a useless-to-legendary underdog system that mistakes him for Chen Mo, a good-for-nothing from the shantytown who is believed to be dead. Playing along with the mistake, he rescues Chen Mo's younger sister, Chen Nian, and enters the third-rate Starfall Academy of supernatural abilities under the assumed identity of Lin Mo. Starting out as an E-rank good-for-nothing with a mixed and impure ability, mocked by everyone, he secretly conceals his true strength while steadily rising through the ranks. With rewards from the system, Lin Yan overcomes one crisis after another, protects the academy and innocent people, and gradually uncovers a shocking conspiracy involving the Dark Domain's infiltration of the righteous world.