At the Meng family's coming-of-age ceremony, their daughter suddenly suffers a severe seafood allergy, revealing shocking doubts about her identity: the adopted daughter is not biologically related to them, and their biological daughter, Su Xinglan, was switched by their servant, Qin Guifang, eighteen years ago. Meng Shaoting secretly investigates, piecing together the truth through hospital records and evidence from the countryside. Su Xinglan quietly enters the Meng household, carefully navigating the schemes of the adopted daughter and Qin Guifang, who join forces to frame her. At the birthday banquet, all the evidence comes to light, Qin Guifang's crimes are exposed, and the Meng family finally welcomes their true daughter home. After eighteen years of living the wrong life, everything is finally set right.