Bai Fei Wan, a twenty-six-year-old PhD holder from the twenty-fifth century, is reborn into the body of a young woman in a fictional historical dynasty after being caught in an avalanche in Tibet. Adopted by the Bai family, she grows up as their cherished daughter, using her modern knowledge to help her family improve their financial status. When the Emperor issues a large-scale Imperial Harem Draft, Bai Fei Wan is selected to become a concubine of Jin Wang, the ninth prince. Her family initially attempts to fake her death to save her, but she refuses, knowing that discovery would ruin them all. She decides to enter the prince's mansion, choosing Jin Wang over other princes because she believes he is the safest option given his current standing.
Upon entering Jin Wang Manor, Bai Fei Wan is assigned to Qingya Courtyard, the most remote residence in the rear courtyard. She brings her loyal maid, Zi Zhu, and three new servants. Through her maid Ziyu, she learns the layout of the mansion: Jin Wang has a Wangfei, Consort Dong, who is desperate for a son to secure her position, and several other concubines. Bai Fei Wan realizes she has transmigrated into a novel titled "The Concubine's Unfading Favor in Stratagems." In the story, Jin Wang is a talented prince who is poisoned by rival factions, rendering him unable to have children. Despite being the Emperor's favorite and holding significant military power, Jin Wang is ultimately assassinated by the Crown Prince and Prince Rui, who collude with foreign enemies. Bai Fei Wan understands that her family will be implicated and killed regardless of which prince wins the throne.
Determined to survive, Bai Fei Wan adopts a passive strategy, avoiding political intrigue and focusing on her daily life of calligraphy, embroidery, and flower arrangement. She hopes to remain invisible until she can find a way to escape or protect her family. For two months, Jin Wang neglects the rear courtyard due to official duties, leaving Bai Fei Wan without his favor. During this time, she endures poor treatment from the kitchen staff, who reduce her meals to vegetarian dishes. Her rival, Nan Shiqie, mocks her for lacking favor, but Bai Fei Wan remains indifferent.
The turning point occurs when Jin Wang returns from a business trip and unexpectedly visits the small garden behind Bai Fei Wan's courtyard. He observes her painting and is struck by her beauty and the unique quality of the paper she uses. Intrigued, he initiates a conversation, and she explains that she made the paper herself. Impressed, Jin Wang takes the painting and promises to visit her. He later dines with her in her courtyard, noticing the poor quality of her food and ordering better meals. Their interaction reveals a growing mutual interest, with Jin Wang finding her refreshing and Bai Fei Wan recognizing his importance. Despite her initial plan to remain a "salted fish," Bai Fei Wan now faces the challenge of navigating her relationship with Jin Wang while trying to alter the tragic fate foretold in the novel.
