Zhu Jia, a recent university graduate and orphan raised by foster parents, dies in a car accident during a trip with classmates and transmigrates into the body of a third female supporting character in the melodramatic novel The Young Master's Childhood Sweetheart. She awakens in a luxurious bedroom as Zhu Jia, the second daughter of a nouveau riche family who has just married the cold, aloof male protagonist, Mo Yichen, in a contractual one-year union. The system 8888 reveals her original fate: she will be cast out after discovering Mo Yichen brought home an illegitimate son, her family will be ruined, and she will suffer a tragic death five years later regardless of her actions. To survive, she must accumulate three million points by raising the infant, Xiao Wen, who is only twenty days old.
Zhu Jia accepts her new reality and begins learning childcare skills through the system's training modules, which cover feeding, diaper changing, bathing, and early education. She discovers that the original host had been volatile and abusive toward the baby, but Zhu Jia approaches caregiving with scientific precision and genuine affection. She immediately sends away the incompetent nannies Mo Yichen provided and takes full responsibility for Xiao Wen's daily care. Her behavior shifts dramatically from the original character's erratic temper to calm competence, confusing Mo Yichen, who returns home early from abroad to investigate. He observes her interacting with the baby and notices the stark contrast in her demeanor, yet remains suspicious of her motives.
Zhu Jia navigates the challenges of caring for a newborn while managing the social expectations of the Mo family. She purchases extensive baby supplies, including a car seat and a nursery, and prepares for Xiao Wen's full moon banquet. During the event, she encounters Mo Yichen's family, including his father Mo Ronghua, his stepmother, and his half-siblings. She also reconnects with her biological father, Zhu Tianyao, with whom she had a strained relationship due to her previous obsession with Mo Yichen. The banquet serves as a public introduction of Xiao Wen as the Mo family heir, solidifying Zhu Jia's position as the child's legal mother.
As Zhu Jia continues to care for Xiao Wen, she earns points steadily and begins to form a bond with the infant. Mo Yichen watches her progress with growing curiosity, noting her dedication and the positive changes in the household atmosphere. He begins to question whether her transformation is genuine or a calculated act. Meanwhile, Zhu Jia focuses on her goal of surviving the year-long contract and escaping her tragic fate. She balances her new role as a mother with her desire to maintain her independence, planning to leave the Mo family once she has secured enough points to change her destiny. The story follows her daily efforts to master parenting while navigating the complex dynamics of a wealthy, aristocratic family.
