Hannah Smith got drunk and walked into the wrong hot spring pool, accidentally saving Andrew Pierce who was drugged. Andrew Pierce woke up and saw Katie Smith, thinking she had saved him. Katie Smith made a mistake by taking away her son and pretending to be her and Andrew Pierce's child after Hannah Smith gave birth to twins. Five years later, Hannah Smith's daughter was diagnosed with leukemia, and only her biological father's bone marrow transplant could save her. While looking for her father to earn surgery fees, Hannah Smith applied to become a nanny for Pierce's family. Andrew Pierce's son has autism and only wants a younger sister. Andrew Pierce unexpectedly discovered that he also had a daughter, and together with his grandfather, they offered a heavy reward to search for her.