The film "Once Upon a Time" is adapted from Tangqi Gangzi's novel of the same name. It tells the story of the celestial prince Yehua and the mortal woman Susu, who fall in love. After Susu becomes pregnant, Yehua takes her to the heavenly realm. Deceived by others, Susu jumps from the Zhuxian Terrace after giving birth to her child, only to regain her identity as the goddess Bai Qian. Beneath the peach blossom tree, when Yehua meets Bai Qian again, their unbreakable bond leads them to experience another cycle of love and loss.