Charlotte, the adopted daughter of the Harrington family, is maliciously drugged and framed by her stepsister Isabella at her engagement banquet. Locked in a tower, she unexpectedly becomes entangled with William, the heir of the Ashford family. Afterwards, Charlotte becomes pregnant out of wedlock and is cast out of the house by Isabella. For eight years, Charlotte raises her son Leo alone, living in hardship. An alumni dance reunites the three. William recognizes Charlotte—whom he has been searching for over the past eight years—by a ruby pendant left by his mother. At this time, forced by poverty, Charlotte is working at William's hotel. Coincidentally, William is being pressured by his grandmother to marry, so the two sign a three-month contract to pretend to be a couple. As they spend time together, William discovers that Leo not only closely resembles him in looks and habits but also shares the same inherited peanut allergy. He realizes that Leo is his son. Isabella keeps framing and harming Charlotte and her son, but her schemes are gradually exposed, and the truth about the drugging and the identity swap from that year also comes to light. After many twists and turns, Isabella suffers the consequences of her own actions, and Charlotte isformally recognized as a true member of the Harrington family. Leo successfully undergoes surgery and recovers. The contract eventually blossoms into genuine love. Charlotte and William overcome all obstacles, and the family of three is finally happily united.