Chemistry Ph.D. student Su Wanqing picks up an ancient seal belonging to Fan Xiwen at Yunlong Park, accidentally time-traveling to Pengcheng in the Northern Song Dynasty and becoming a kitchen maid in the Prefect's Mansion. Amidst floods and a salt famine, she uses chemical methods to purify refined salt; after a great disaster brings an outbreak of plague, she extracts medicine using ancient methods to save the common people. She enters the Zichen Mansion following Fan Xiwen, where her poetry gathering dazzles everyone and further assists him in drafting reform manuscripts, with the phrase "everyone like a dragon" angering the imperial court. When crisis strikes, the ancient seal glows to send her back to modern times. A millennium later, Su Wanqing recreates the dream of Peach Blossom Spring of that year using Song-style gardens, gazing across time and space at the old friend in the shimmering light.