Gu Qingcheng, a young florist from the "Flower Capital" of Pingcheng, is guided by a mysterious firefly and accidentally inhales the "flower spirit" of a white peony while trying to save it. Little does she know, this white peony is actually Lyu Gengyun, a thousand-year-old half-demon. Since childhood, Gu Qingcheng has been determined to revive 9,999 flowers, following her father's dying wish, believing that once she succeeds, the Flower Immortal Lord will take her to the heavens to meet the person she longs for. That fateful night, Lyu Gengyun awakens within a giant white peony, and the sight convinces Gu Qingcheng that he is the Flower Immortal Lord. She immediately pledges herself as his disciple. Lyu Gengyun, seeking a way to extract the flower spirit from within her and uncover the truth behind his parents' wrongful fate, has no choice but to stay by her side under a false identity, waiting for the right opportunity. But to his shock, Gu Qingcheng turns out to be the infamous "Flower Thief" feared by many… As the two embark on a series of magical adventures, their hearts gradually draw closer. Yet, with the cycle of fate looming over them and the real Flower Immortal Lord  making his appearance, they are once again faced with a new wave of choices and challenges.