Han Jae-hee (Park Si-yeon), whose mother is a prostitute, whose father is unknown, and whose only brother is deeply involved in gambling and even sold her to a brothel owner, has always wanted to escape from the slums since she was a child. The moment she ran into Jiang Malu's (Song Joong-ki) house, she also jumped deeply into his heart and became a beacon in his heart. In order to take the blame for his beloved Jae-hee, Malu went from being an excellent medical student to a murderer in a labor camp. Jae-hee, who promised "I will pay this debt for the rest of my life", still married the powerful Chairman Xu. After being ruthlessly betrayed by Jae-hee, Malu decided to use Chairman Xu's daughter Xu Enqi (Moon Chae-won) to take revenge on them after being released from prison. In the process of revenge, Malu gradually discovered that Enqi just made herself look strong and could not be bullied. In fact, she just needed to protect herself from harm. Gradually, this man with a completely different life trajectory from himself walked into Enqi's heart, and also learned about his relationship with Jae-hee. Malu, who didn't have time to tell Enqi about his worries, suffered from brain damage and went to the United States after surgery. Seven years later, Jiang Malu returned from studying in the United States and became a doctor. Did he lose his memory due to the operation seven years ago? Where will his relationship with Enqi go?