Skilled in poison arts, Liu Muyan transmigrates into General Lane's daughter. Forced by Natalie Lane into a substitute marriage to Crown Prince Chu Xuze, she saves him from a Gu curse. Liu Muyan thwarts Natalie's assassination attempts. Natalie plants a Twin Gu Worm. Southern Border lord reveals Liu Muyan as the Southern Border Saint. Facing the empress's conspiracy, Liu Muyan and the Crown Prince, with Southern Border forces, put down the palace coup. The Crown Prince ascends.