Margaret Winst, a 60-year-old retired chemistry professor, marries Liam, a 27-year-old influencer. One week later, Liam dies in a car crash. Police discover his brakes were tampered with—murder.
At the funeral, Margaret's estranged stepson Derek appears. He is Liam's half-brother. Suspicious, Margaret investigates. She finds Liam's diary mentioning coffee with Derek. Detective Jack confirms the murder but lacks evidence.
Margaret hires an actor who looks like Liam. The actor calls Derek, pretending to be Liam, and tricks him into confessing on tape. Derek is arrested and sentenced to life in prison.
Margaret donates her entire fortune to a foundation helping victims of financial fraud by family members. She moves into a nursing home, where she meets Lily, a young caregiver, and Henry, a retired judge. She helps Lily go to college, writes a book about her experience, and begins rebuilding her life through service to others.